draft-ietf-xmpp-core-05.txt   draft-ietf-xmpp-core-06.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft J. Miller Internet-Draft J. Miller
Expires: August 31, 2003 Jabber Software Foundation Expires: September 24, 2003 Jabber Software Foundation
March 2, 2003 March 26, 2003
XMPP Core XMPP Core
draft-ietf-xmpp-core-05 draft-ietf-xmpp-core-06
Status of this Memo Status of this Memo
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Abstract Abstract
This document describes the core features of the Extensible Messaging This document describes the core features of the Extensible Messaging
and Presence Protocol (XMPP), a protocol for streaming XML in and Presence Protocol (XMPP), a protocol for streaming XML in near-
near-real-time that is used mainly for the purpose of instant real-time that is used mainly for the purpose of instant messaging
messaging (IM) and presence by the servers, clients, and other (IM) and presence by the servers, clients, and other applications
applications that comprise the Jabber network. that comprise the Jabber network.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Intellectual Property Notice . . . . . . . . . . . . . . . . 5 1.4 Intellectual Property Notice . . . . . . . . . . . . . . . . 5
2. Generalized Architecture . . . . . . . . . . . . . . . . . . 6 2. Generalized Architecture . . . . . . . . . . . . . . . . . . 6
2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Server . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 Server . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . 8 3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . 8
3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . . 8 3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . . 8
3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . . 8
3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . . 9 3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . . 9
4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . 10 4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3 Stream Attributes . . . . . . . . . . . . . . . . . . . . . 11 4.3 Stream Attributes . . . . . . . . . . . . . . . . . . . . . 11
4.4 Namespace Declarations . . . . . . . . . . . . . . . . . . . 12 4.4 Namespace Declarations . . . . . . . . . . . . . . . . . . . 12
4.5 Stream Features . . . . . . . . . . . . . . . . . . . . . . 13 4.5 Stream Features . . . . . . . . . . . . . . . . . . . . . . 13
4.6 Stream Errors . . . . . . . . . . . . . . . . . . . . . . . 13 4.6 Stream Errors . . . . . . . . . . . . . . . . . . . . . . . 14
4.6.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.6.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.6.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.6.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.6.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.6.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.6.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 16 4.6.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 16
4.7 Simple Streams Example . . . . . . . . . . . . . . . . . . . 16 4.7 Simple Streams Example . . . . . . . . . . . . . . . . . . . 16
5. Stream Encryption . . . . . . . . . . . . . . . . . . . . . 18 5. Stream Encryption . . . . . . . . . . . . . . . . . . . . . 18
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . . 19 5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . . 19
5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . . 21 5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . . 21
6. Stream Authentication . . . . . . . . . . . . . . . . . . . 24 6. Stream Authentication . . . . . . . . . . . . . . . . . . . 24
6.1 SASL Authentication . . . . . . . . . . . . . . . . . . . . 24 6.1 SASL Authentication . . . . . . . . . . . . . . . . . . . . 24
6.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 24 6.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 26 6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 26
6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . . 27 6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . . 27
6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . . 29 6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . . 29
6.2 Dialback Authentication . . . . . . . . . . . . . . . . . . 31 6.2 Dialback Authentication . . . . . . . . . . . . . . . . . . 32
6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . . 34 6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . . 34
7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 37 7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 37
7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . . 37 7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . . 37
7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . . 38 7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . . 38
7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . . 39 7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . . 39
7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 39 7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . . 40 7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . . 40
7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . . 41 7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . . 41
7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 41
7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . . 43 7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . . 43
7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . . 44 7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . . 44
7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 45 7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 45
7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 46 7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 47 7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 47
8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 48 8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 48
8.1 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . 48 8.1 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.2 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 48 8.2 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.3 Character Encodings . . . . . . . . . . . . . . . . . . . . 48 8.3 Character Encodings . . . . . . . . . . . . . . . . . . . . 48
8.4 Inclusion of Text Declaration . . . . . . . . . . . . . . . 48 8.4 Inclusion of Text Declaration . . . . . . . . . . . . . . . 48
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 49 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 49
10. Internationalization Considerations . . . . . . . . . . . . 50 10. Internationalization Considerations . . . . . . . . . . . . 50
11. Security Considerations . . . . . . . . . . . . . . . . . . 51 11. Security Considerations . . . . . . . . . . . . . . . . . . 51
11.1 Client-to-Server Communications . . . . . . . . . . . . . . 51 11.1 High Security . . . . . . . . . . . . . . . . . . . . . . . 51
11.2 Server-to-Server Communications . . . . . . . . . . . . . . 51 11.2 Client-to-Server Communications . . . . . . . . . . . . . . 51
11.3 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . 51 11.3 Server-to-Server Communications . . . . . . . . . . . . . . 51
11.4 Minimum Security Mechanisms . . . . . . . . . . . . . . . . 51 11.4 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . 52
11.5 Mandatory to Implement Technologies . . . . . . . . . . . . 52
References . . . . . . . . . . . . . . . . . . . . . . . . . 53 References . . . . . . . . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 55 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 55
A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 56 A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 56
A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . . 56 A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . . 56
A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 57 A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 57
A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 57 A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 57
A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 58 A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 58
A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . . 59 A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . . 59
A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . . 62 A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . . 62
A.7 Stream error namespace . . . . . . . . . . . . . . . . . . . 65 A.7 Stream error namespace . . . . . . . . . . . . . . . . . . . 65
A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . . 66 A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . . 66
B. Provisional Namespace Names . . . . . . . . . . . . . . . . 68 B. Provisional Namespace Names . . . . . . . . . . . . . . . . 68
C. Revision History . . . . . . . . . . . . . . . . . . . . . . 69 C. Revision History . . . . . . . . . . . . . . . . . . . . . . 69
C.1 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 69 C.1 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . . 69
C.2 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 69 C.2 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 69
C.3 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 69 C.3 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 69
C.4 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 69 C.4 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 69
C.5 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 70 C.5 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 70
C.6 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 70 C.6 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 70
Intellectual Property and Copyright Statements . . . . . . . 72 C.7 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 70
Full Copyright Statement . . . . . . . . . . . . . . . . . . 72
1. Introduction 1. Introduction
1.1 Overview 1.1 Overview
The Extensible Messaging and Presence Protocol (XMPP) is an open XML The Extensible Messaging and Presence Protocol (XMPP) is an open XML
[1] protocol for near-real-time messaging, presence, and [1] protocol for near-real-time messaging, presence, and request-
request-response services. The protocol was developed originally response services. The protocol was developed originally within the
within the Jabber community starting in 1998, and has continued to Jabber community starting in 1998, and has continued to evolve under
evolve under the auspices of the Jabber Software Foundation [2] the auspices of the Jabber Software Foundation [2] (since June 2001)
(since June 2001) and the XMPP WG (since November 2002). The current and the XMPP WG (since November 2002). The current document defines
document defines the core features of XMPP; XMPP IM [3] defines the the core features of XMPP; XMPP IM [3] defines the extensions
extensions necessary to provide the instant messaging (IM) and necessary to provide the instant messaging (IM) and presence
presence functionality defined in RFC 2779 [4]. functionality defined in RFC 2779 [4].
1.2 Terminology 1.2 Terminology
The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC "OPTIONAL" in this document are to be interpreted as described in RFC
2119 [5]. 2119 [5].
1.3 Discussion Venue 1.3 Discussion Venue
skipping to change at page 6, line 10 skipping to change at page 6, line 10
identifying namespaces and other protocol syntax. Jabber[tm] is a identifying namespaces and other protocol syntax. Jabber[tm] is a
registered trademark of Jabber, Inc. Jabber, Inc. grants permission registered trademark of Jabber, Inc. Jabber, Inc. grants permission
to the IETF for use of the Jabber trademark in association with this to the IETF for use of the Jabber trademark in association with this
specification and its successors, if any. specification and its successors, if any.
2. Generalized Architecture 2. Generalized Architecture
2.1 Overview 2.1 Overview
Although XMPP is not wedded to any specific network architecture, to Although XMPP is not wedded to any specific network architecture, to
this point it has usually been implemented via a typical this point it has usually been implemented via a typical client-
client-server architecture, wherein a client utilizing XMPP accesses server architecture, wherein a client utilizing XMPP accesses a
a server over a TCP [6] socket. server over a TCP [6] socket.
The following diagram provides a high-level overview of this The following diagram provides a high-level overview of this
architecture (where "-" represents communications that use XMPP and architecture (where "-" represents communications that use XMPP and
"=" represents communications that use any other protocol). "=" represents communications that use any other protocol).
C1 - S1 - S2 - C3 C1 - S1 - S2 - C3
/ \ / \
C2 - G1 = FN1 = FC1 C2 - G1 = FN1 = FC1
The symbols are as follows: The symbols are as follows:
skipping to change at page 7, line 4 skipping to change at page 7, line 6
and to route appropriately-addressed XML data "stanzas" among such and to route appropriately-addressed XML data "stanzas" among such
entities over XML streams. Most XMPP-compliant servers also assume entities over XML streams. Most XMPP-compliant servers also assume
responsibility for the storage of data that is used by clients (e.g., responsibility for the storage of data that is used by clients (e.g.,
contact lists for users of XMPP-based IM applications); in this case, contact lists for users of XMPP-based IM applications); in this case,
the XML data is processed directly by the server itself on behalf of the XML data is processed directly by the server itself on behalf of
the client and is not routed to another entity. Compliant server the client and is not routed to another entity. Compliant server
implementations MUST ensure in-order processing of XML stanzas implementations MUST ensure in-order processing of XML stanzas
received from connected clients, servers, and services. received from connected clients, servers, and services.
2.3 Client 2.3 Client
Most clients connect directly to a server over a TCP socket and use Most clients connect directly to a server over a TCP socket and use
XMPP to take full advantage of the functionality provided by a server XMPP to take full advantage of the functionality provided by a server
and any associated services, although it must be noted that there is and any associated services, although it must be noted that there is
no necessary coupling of an XML stream to a TCP socket (e.g., a no necessary coupling of an XML stream to a TCP socket (e.g., a
client COULD connect via HTTP polling or some other mechanism). client COULD connect via HTTP polling or some other mechanism).
Multiple resources (e.g., devices or locations) MAY connect Multiple resources (e.g., devices or locations) MAY connect
simultaneously to a server on behalf of each authorized client, with simultaneously to a server on behalf of each authorized client, with
each resource connecting over a discrete TCP socket and each resource connecting over a discrete TCP socket and
differentiated by the resource identifier of a JID (Section 3) (e.g., differentiated by the resource identifier of a JID (Section 3) (e.g.,
user@domain/home vs. user@domain/work). The port registered with the user@domain/home vs. user@domain/work). The port registered with
IANA [7] for connections between a Jabber client and a Jabber server the IANA [7] for connections between a Jabber client and a Jabber
is 5222. For further details about client-to-server communications server is 5222. For further details about client-to-server
expressly for the purpose of instant messaging and presence, refer to communications expressly for the purpose of instant messaging and
XMPP IM [3]. presence, refer to XMPP IM [3].
2.4 Gateway 2.4 Gateway
A gateway is a special-purpose server-side service whose primary A gateway is a special-purpose server-side service whose primary
function is to translate XMPP into the protocol(s) of another function is to translate XMPP into the protocol(s) of another
messaging system, as well as to translate the return data back into messaging system, as well as to translate the return data back into
XMPP. Examples are gateways to SIMPLE, Internet Relay Chat (IRC), XMPP. Examples are gateways to SIMPLE, Internet Relay Chat (IRC),
Short Message Service (SMS), SMTP, and foreign instant messaging Short Message Service (SMS), SMTP, and foreign instant messaging
networks such as Yahoo!, MSN, ICQ, and AIM. Communications between networks such as Yahoo!, MSN, ICQ, and AIM. Communications between
gateways and servers, and between gateways and the foreign messaging gateways and servers, and between gateways and the foreign messaging
system, are not defined in this document. system, are not defined in this document.
2.5 Network 2.5 Network
Because each server is identified by a network address (typically a Because each server is identified by a network address (typically a
DNS hostname) and because server-to-server communications are a DNS hostname) and because server-to-server communications are a
straightforward extension of the client-to-server protocol, in straightforward extension of the client-to-server protocol, in
practice the system consists of a network of servers that practice the system consists of a network of servers that inter-
inter-communicate. Thus user-a@domain1 is able to exchange messages, communicate. Thus user-a@domain1 is able to exchange messages,
presence, and other information with user-b@domain2. This pattern is presence, and other information with user-b@domain2. This pattern is
familiar from messaging protocols (such as SMTP) that make use of familiar from messaging protocols (such as SMTP) that make use of
network addressing standards. Upon opening a TCP socket on the network addressing standards. Upon opening a TCP socket on the IANA-
IANA-registered port 5269, there are two methods for negotiating a registered port 5269, there are two methods for negotiating a
connection between any two servers: server dialback (Section 6.2) and connection between any two servers: server dialback (Section 6.2) and
SASL authentication (Section 6.1). SASL authentication (Section 6.1).
3. Addressing Scheme 3. Addressing Scheme
3.1 Overview 3.1 Overview
An entity is anything that can be considered a network endpoint An entity is anything that can be considered a network endpoint
(i.e., an ID on the network) and that can communicate using XMPP. All (i.e., an ID on the network) and that can communicate using XMPP.
such entities are uniquely addressable in a form that is consistent All such entities are uniquely addressable in a form that is
with RFC 2396 [8]. In particular, a valid Jabber Identifier (JID) consistent with RFC 2396 [8]. In particular, a valid Jabber
contains a set of ordered elements formed of a domain identifier, Identifier (JID) contains a set of ordered elements formed of a
node identifier, and resource identifier in the following format: domain identifier, node identifier, and resource identifier in the
[node@]domain[/resource]. following format: [node@]domain[/resource].
All JIDs are based on the foregoing structure. The most common use of All JIDs are based on the foregoing structure. The most common use
this structure is to identify an IM user, the server to which the of this structure is to identify an IM user, the server to which the
user connects, and the user's active session or connection (e.g., a user connects, and the user's active session or connection (e.g., a
specific client) in the form of user@domain/resource. However, node specific client) in the form of user@domain/resource. However, node
types other than clients are possible; for example, a specific chat types other than clients are possible; for example, a specific chat
room offered by a multi-user chat service could be addressed as room offered by a multi-user chat service could be addressed as
<room@service> (where "room" is the name of the chat room and <room@service> (where "room" is the name of the chat room and
"service" is the hostname of the multi-user chat service) and a "service" is the hostname of the multi-user chat service) and a
specific occupant of such a room could be addressed as <room@service/ specific occupant of such a room could be addressed as <room@service/
nick> (where "nick" is the occupant's room nickname). Many other JID nick> (where "nick" is the occupant's room nickname). Many other JID
types are possible (e.g., <domain/resource> could be a server-side types are possible (e.g., <domain/resource> could be a server-side
script or service). script or service).
skipping to change at page 9, line 5 skipping to change at page 9, line 5
Name. A domain identifier MUST conform to RFC 952 [9] and RFC 1123 Name. A domain identifier MUST conform to RFC 952 [9] and RFC 1123
[10]. A domain identifier MUST be no more than 1023 bytes in length [10]. A domain identifier MUST be no more than 1023 bytes in length
and MUST conform to the nameprep [11] profile of stringprep [12]. and MUST conform to the nameprep [11] profile of stringprep [12].
3.3 Node Identifier 3.3 Node Identifier
The node identifier is an optional secondary identifier. It usually The node identifier is an optional secondary identifier. It usually
represents the entity requesting and using network access provided by represents the entity requesting and using network access provided by
the server or gateway (i.e., a client), although it can also the server or gateway (i.e., a client), although it can also
represent other kinds of entities (e.g., a multi-user chat room represent other kinds of entities (e.g., a multi-user chat room
associated with a multi-user chat service). The entity represented by associated with a multi-user chat service). The entity represented
a node identifier is addressed within the context of a specific by a node identifier is addressed within the context of a specific
domain; within IM applications of XMPP this address is called a "bare domain; within IM applications of XMPP this address is called a "bare
JID" and is of the form <user@domain>. JID" and is of the form <user@domain>.
A node identifier MUST be no more than 1023 bytes in length and MUST A node identifier MUST be no more than 1023 bytes in length and MUST
conform to the nodeprep [13] profile of stringprep [12]. conform to the nodeprep [13] profile of stringprep [12].
3.4 Resource Identifier 3.4 Resource Identifier
The resource identifer is an optional tertiary identifier. It usually The resource identifer is an optional tertiary identifier. It
represents a specific session, connection (e.g., a device or usually represents a specific session, connection (e.g., a device or
location), or object (e.g., a participant in a multi-user chat room) location), or object (e.g., a participant in a multi-user chat room)
belonging to the entity associated with a node identifier. An entity belonging to the entity associated with a node identifier. An entity
may maintain multiple resources simultaneously. may maintain multiple resources simultaneously.
A resource identifier MUST be no more than 1023 bytes in length and A resource identifier MUST be no more than 1023 bytes in length and
MUST conform to the resourceprep [14] profile of stringprep [12]. MUST conform to the resourceprep [14] profile of stringprep [12].
4. XML Streams 4. XML Streams
4.1 Overview 4.1 Overview
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client or server) to a receiving entity (usually a server), client or server) to a receiving entity (usually a server),
normally over a TCP socket. An XML stream corresponds to the normally over a TCP socket. An XML stream corresponds to the
initiating entity's session with the receiving entity. The start initiating entity's session with the receiving entity. The start
of the XML stream is denoted unambiguously by an opening XML of the XML stream is denoted unambiguously by an opening XML
<stream> tag with appropriate attributes and namespace <stream> tag with appropriate attributes and namespace
declarations. The end of the XML stream is denoted unambiguously declarations. The end of the XML stream is denoted unambiguously
be a closing XML </stream> tag. be a closing XML </stream> tag.
Definition of XML stanza: An XML stanza is a discrete semantic unit Definition of XML stanza: An XML stanza is a discrete semantic unit
of structured information that is sent from one entity to another of structured information that is sent from one entity to another
over an XML stream. An XML stanza exists at the direct child level over an XML stream. An XML stanza exists at the direct child
of the root <stream/> element and is said to be well-balanced if level of the root <stream/> element and is said to be well-
it matches production [43] content of the XML specification [1]). balanced if it matches production [43] content of the XML
The start of any XML stanza is denoted unambiguously by the specification [1]). The start of any XML stanza is denoted
element start tag at depth=1 (e.g., <presence>), and the end of unambiguously by the element start tag at depth=1 (e.g.,
any XML stanza is denoted unambiguously by the corresponding close <presence>), and the end of any XML stanza is denoted
tag at depth=1 (e.g., </presence>). An XML stanza MAY contain unambiguously by the corresponding close tag at depth=1 (e.g., </
child elements or CDATA sections as necessary in order to convey presence>). An XML stanza MAY contain child elements or CDATA
the desired information. sections as necessary in order to convey the desired information.
Consider the example of a client's session with a server. In order to Consider the example of a client's session with a server. In order
connect to a server, a client must initiate an XML stream by sending to connect to a server, a client must initiate an XML stream by
an opening <stream> tag to the server, optionally preceded by a text sending an opening <stream> tag to the server, optionally preceded by
declaration specifying the XML version supported and the character a text declaration specifying the XML version supported and the
encoding. The server SHOULD then reply with a second XML stream back character encoding. The server SHOULD then reply with a second XML
to the client, again optionally preceded by a text declaration. Once stream back to the client, again optionally preceded by a text
the client has authenticated with the server (see Section 6), the declaration. Once the client has authenticated with the server (see
client MAY send an unlimited number of XML stanzas over the stream to Section 6), the client MAY send an unlimited number of XML stanzas
any recipient on the network. When the client desired to close the over the stream to any recipient on the network. When the client
stream, it simply sends a closing </stream> tag to the server desired to close the stream, it simply sends a closing </stream> tag
(alternatively, the session may be closed by the server). to the server (alternatively, the session may be closed by the
server).
Thus a client's session with a server can be seen as two open-ended Thus a client's session with a server can be seen as two open-ended
XML documents that are built up through the accumulation of the XML XML documents that are built up through the accumulation of the XML
stanzas sent over the two XML streams (i.e., one from the client to stanzas sent over the two XML streams (i.e., one from the client to
the server and one from the server to the client), and the root the server and one from the server to the client), and the root
<stream/> element can be considered the document entity for each <stream/> element can be considered the document entity for each
document. In essence, then, an XML stream acts as an envelope for all document. In essence, then, an XML stream acts as an envelope for
the XML stanzas sent during a session. We can represent this all the XML stanzas sent during a session. We can represent this
graphically as follows: graphically as follows:
|-------------------| |-------------------|
| <stream> | | <stream> |
|-------------------| |-------------------|
| <message to=''> | | <message to=''> |
| <body/> | | <body/> |
| </message> | | </message> |
|-------------------| |-------------------|
| <presence to=''> | | <presence to=''> |
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| ... | | ... |
|-------------------| |-------------------|
| </stream> | | </stream> |
|-------------------| |-------------------|
4.2 Restrictions 4.2 Restrictions
XML streams are used to transport a subset of XML. Specifically, XML XML streams are used to transport a subset of XML. Specifically, XML
streams SHOULD NOT contain processing instructions, predefined streams SHOULD NOT contain processing instructions, predefined
entities (as defined in Section 4.6 of the XML specification [1]), entities (as defined in Section 4.6 of the XML specification [1]),
comments, or DTDs. Any such XML data SHOULD be ignored by a compliant comments, or DTDs. Any such XML data SHOULD be ignored by a
implementation. compliant implementation.
4.3 Stream Attributes 4.3 Stream Attributes
The attributes of the stream element are as follows: The attributes of the stream element are as follows:
o to -- The 'to' attribute SHOULD be used only in the XML stream o to -- The 'to' attribute SHOULD be used only in the XML stream
from the initiating entity to the receiving entity, and MUST be from the initiating entity to the receiving entity, and MUST be
set to the XMPP address of the receiving entity. There SHOULD be set to the XMPP address of the receiving entity. There SHOULD be
no 'to' attribute set in the XML stream by which the receiving no 'to' attribute set in the XML stream by which the receiving
entity replies to the initiating entity; however, if a 'to' entity replies to the initiating entity; however, if a 'to'
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o from -- The 'from' attribute SHOULD be used only in the XML stream o from -- The 'from' attribute SHOULD be used only in the XML stream
from the receiving entity to the initiating entity, and MUST be from the receiving entity to the initiating entity, and MUST be
set to the XMPP address of the receiving entity granting access to set to the XMPP address of the receiving entity granting access to
the initiating entity. There SHOULD be no 'from' attribute on the the initiating entity. There SHOULD be no 'from' attribute on the
XML stream sent from the initiating entity to the receiving XML stream sent from the initiating entity to the receiving
entity; however, if a 'from' attribute is included, it SHOULD be entity; however, if a 'from' attribute is included, it SHOULD be
ignored by the receiving entity. ignored by the receiving entity.
o id -- The 'id' attribute SHOULD be used only in the XML stream o id -- The 'id' attribute SHOULD be used only in the XML stream
from the receiving entity to the initiating entity. This attribute from the receiving entity to the initiating entity. This
is a unique identifier created by the receiving entity to function attribute is a unique identifier created by the receiving entity
as a session key for the initiating entity's session with the to function as a session key for the initiating entity's session
receiving entity. There SHOULD be no 'id' attribute on the XML with the receiving entity. There SHOULD be no 'id' attribute on
stream sent from the initiating entity to the receiving entity; the XML stream sent from the initiating entity to the receiving
however, if an 'id' attribute is included, it SHOULD be ignored by entity; however, if an 'id' attribute is included, it SHOULD be
the receiving entity. ignored by the receiving entity.
o version -- The 'version' attribute MAY be used in the XML stream o version -- The 'version' attribute MAY be used in the XML stream
from the initiating entity to the receiving entity in order signal from the initiating entity to the receiving entity in order signal
compliance with the protocol defined herein; this is done by compliance with the protocol defined herein; this is done by
setting the value of the attribute to "1.0". If the initiating setting the value of the attribute to "1.0". If the initiating
entity includes the version attribute and the receiving entity entity includes the version attribute and the receiving entity
supports XMPP 1.0, the receiving entity MUST reciprocate by supports XMPP 1.0, the receiving entity MUST reciprocate by
including the attribute in its response. including the attribute in its response.
We can summarize these values as follows: We can summarize these values as follows:
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o jabber:server -- this default namespace is declared when the o jabber:server -- this default namespace is declared when the
stream is used for communications between two servers stream is used for communications between two servers
The jabber:client and jabber:server namespaces are nearly identical The jabber:client and jabber:server namespaces are nearly identical
but are used in different contexts (client-to-server communications but are used in different contexts (client-to-server communications
for jabber:client and server-to-server communications for for jabber:client and server-to-server communications for
jabber:server). The only difference between the two is that the 'to' jabber:server). The only difference between the two is that the 'to'
and 'from' attributes are OPTIONAL on stanzas sent within and 'from' attributes are OPTIONAL on stanzas sent within
jabber:client, whereas they are REQUIRED on stanzas sent within jabber:client, whereas they are REQUIRED on stanzas sent within
jabber:server. If a compliant implementation accepts a stream that is jabber:server. If a compliant implementation accepts a stream that
scoped by the 'jabber:client' or 'jabber:server' namespace, it MUST is scoped by the 'jabber:client' or 'jabber:server' namespace, it
support all three core stanza types (message, presence, and IQ) as MUST support all three core stanza types (message, presence, and IQ)
described herein and defined in the schema. as described herein and defined in the schema.
4.5 Stream Features 4.5 Stream Features
The root stream element MAY contain a features child element (e.g., The root stream element MAY contain a features child element (e.g.,
<stream:features/> if the stream namespace prefix is 'stream'). This <stream:features/> if the stream namespace prefix is 'stream'). This
is used to communicate generic stream-level capabilities including is used to communicate generic stream-level capabilities including
stream-level features that can be negotiated as the streams are set stream-level features that can be negotiated as the streams are set
up. If the initiating entity sends a "version='1.0'" flag in its up. If the initiating entity sends a "version='1.0'" flag in its
initiating stream element, the receiving entity MUST send a features initiating stream element, the receiving entity MUST send a features
child element to the initiating entity if there are any capabilities child element to the initiating entity if there are any capabilities
that need to be advertised or features that can be negotiated for the that need to be advertised or features that can be negotiated for the
stream. Currently this is used for SASL and TLS negotiation only, but stream. Currently this is used for SASL and TLS negotiation only,
it could be used for other negotiable features in the future (usage but it could be used for other negotiable features in the future
is defined under Stream Encryption (Section 5) and Stream (usage is defined under Stream Encryption (Section 5) and Stream
Authentication (Section 6) below). If an entity does not understand Authentication (Section 6) below). If an entity does not understand
or support some features, it SHOULD ignore them. or support some features, it SHOULD ignore them.
4.6 Stream Errors 4.6 Stream Errors
The root stream element MAY contain an error child element (e.g., The root stream element MAY contain an error child element (e.g.,
<stream:error/> if the stream namespace prefix is 'stream'). The <stream:error/> if the stream namespace prefix is 'stream'). The
error child MUST be sent by a Jabber entity (usually a server rather error child MUST be sent by a Jabber entity (usually a server rather
than a client) if it perceives that a stream-level error has than a client) if it perceives that a stream-level error has
occurred. occurred.
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o address -- the condition relates to the JID or domain to which the o address -- the condition relates to the JID or domain to which the
stream was addressed stream was addressed
o format -- the condition relates to XML format or structure o format -- the condition relates to XML format or structure
o redirect -- the condition relates to a host redirection o redirect -- the condition relates to a host redirection
o server -- the condition relates to the internal state of the o server -- the condition relates to the internal state of the
server server
The <stream-condition/> element MUST contain a child element that The <stream-condition/> element MUST contain a child element that
specifies a particular stream-level error condition, as defined in specifies a particular stream-level error condition, as defined in
the next section. (Note: the XML namespace name the next section. (Note: the XML namespace name
'urn:ietf:rfc:xmppcore-rfc-number:streams' that scopes the 'urn:ietf:rfc:xmppcore-rfc-number:streams' that scopes the <stream-
<stream-condition/> element adheres to the format defined in RFC 2648 condition/> element adheres to the format defined in RFC 2648 [16].)
[16].)
4.6.3 Conditions 4.6.3 Conditions
The following stream-level error conditions are defined: The following stream-level error conditions are defined:
o <host-gone/> -- the value of the 'to' attribute provided by the o <host-gone/> -- the value of the 'to' attribute provided by the
initiating entity in the stream header corresponds to a hostname initiating entity in the stream header corresponds to a hostname
that is no longer hosted by the server; the associated class is that is no longer hosted by the server; the associated class is
"address". "address".
o <host-unknown/> -- the value of the 'to' attribute provided by the o <host-unknown/> -- the value of the 'to' attribute provided by the
initiating entity in the stream header does not correspond to a initiating entity in the stream header does not correspond to a
hostname that is hosted by the server; the associated class is hostname that is hosted by the server; the associated class is
"address". "address".
o <internal-server-error/> -- the server has experienced a o <internal-server-error/> -- the server has experienced a
misconfiguration or an otherwise-undefined internal server error misconfiguration or an otherwise-undefined internal server error
that prevents it from servicing the stream; the associated class that prevents it from servicing the stream; the associated class
is "server". is "server".
o <invalid-namespace/> -- the stream namespace name is something
other than "http://etherx.jabber.org/streams"; the associated
class is "format".
o <resource-constraint/> -- the server is resource-contrained and is o <resource-constraint/> -- the server is resource-contrained and is
unable to service the stream; the associated class is "server". unable to service the stream; the associated class is "server".
o <see-other-host/> -- the server will not provide service to the o <see-other-host/> -- the server will not provide service to the
initiating entity but is redirecting traffic to another host; this initiating entity but is redirecting traffic to another host; this
element SHOULD contain CDATA specifying the alternate hostname or element SHOULD contain CDATA specifying the alternate hostname or
IP address to which the initiating entity MAY attempt to connect; IP address to which the initiating entity MAY attempt to connect;
the associated class is "redirect". the associated class is "redirect".
o <system-shutdown/> -- the server is being shut down and all active o <system-shutdown/> -- the server is being shut down and all active
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MAY contain CDATA specifying the XMPP version(s) supported by the MAY contain CDATA specifying the XMPP version(s) supported by the
server; the associated class is "format". server; the associated class is "format".
o <xml-not-well-formed/> -- the initiating entity has sent XML that o <xml-not-well-formed/> -- the initiating entity has sent XML that
is not well-formed as defined by the XML specification [1]; the is not well-formed as defined by the XML specification [1]; the
associated class is "format". associated class is "format".
4.6.4 Extensibility 4.6.4 Extensibility
If desired, an XMPP application MAY provide custom error information; If desired, an XMPP application MAY provide custom error information;
this MUST be contained in a properly-namespaced child of the this MUST be contained in a properly-namespaced child of the <stream-
<stream-condition/> element (i.e., the namespace name MUST NOT be one condition/> element (i.e., the namespace name MUST NOT be one of the
of the namespace names defined herein). namespace names defined herein).
4.7 Simple Streams Example 4.7 Simple Streams Example
The following is a stream-based session of a client on a server The following is a stream-based session of a client on a server
(where the "C" lines are sent from the client to the server, and the (where the "C" lines are sent from the client to the server, and the
"S" lines are sent from the server to the client): "S" lines are sent from the server to the client):
A basic session: A basic session:
C: <?xml version='1.0'?> C: <?xml version='1.0'?>
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S: </stream:stream> S: </stream:stream>
5. Stream Encryption 5. Stream Encryption
5.1 Overview 5.1 Overview
XMPP includes a method for securing the stream from tampering and XMPP includes a method for securing the stream from tampering and
eavesdropping. This channel encryption method makes use of the eavesdropping. This channel encryption method makes use of the
Transport Layer Security (TLS) [17] protocol, along with a "STARTTLS" Transport Layer Security (TLS) [17] protocol, along with a "STARTTLS"
extension that is modelled on similar extensions for the IMAP [18], extension that is modelled on similar extensions for the IMAP [18],
POP3 [19], and ACAP [20] protocols as described in RFC 2595 [21]. The POP3 [19], and ACAP [20] protocols as described in RFC 2595 [21].
namespace identifier for the STARTTLS extension is 'http:// The namespace identifier for the STARTTLS extension is 'http://
www.ietf.org/rfc/rfc2595.txt'. TLS may be used between any initiating www.ietf.org/rfc/rfc2595.txt'. TLS may be used between any
entity and any receiving entity (e.g., a stream from a client to a initiating entity and any receiving entity (e.g., a stream from a
server or from one server to another). client to a server or from one server to another).
The following rules MUST be observed: The following rules MUST be observed:
1. If the initiating entity is capable of using the STARTTLS 1. If the initiating entity is capable of using the STARTTLS
extension, it MUST include the "version='1.0'" flag in the extension, it MUST include the "version='1.0'" flag in the
initiating stream header. initiating stream header.
2. If the receiving entity is capable of using the STARTTLS 2. If the receiving entity is capable of using the STARTTLS
extension, it MUST send the <starttls/> element in the defined extension, it MUST send the <starttls/> element in the defined
namespace along with the list of features that it sends in namespace along with the list of features that it sends in
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7. If the TLS negotiation is successful, the receiving entity MUST 7. If the TLS negotiation is successful, the receiving entity MUST
NOT offer the STARTTLS extension to the initiating entity along NOT offer the STARTTLS extension to the initiating entity along
with the other stream features that are offered when the stream with the other stream features that are offered when the stream
is restarted. is restarted.
8. Whether the TLS negotiation results in success or failure, the 8. Whether the TLS negotiation results in success or failure, the
initiating entity SHOULD continue with SASL negotiation. initiating entity SHOULD continue with SASL negotiation.
9. If TLS is used for stream encryption, SASL MUST NOT be used for 9. If TLS is used for stream encryption, SASL MUST NOT be used for
anything but stream authentication (i.e., a security layer MUST anything but stream authentication (i.e., a security layer MUST
NOT be negotiated using SASL). Conversely, if a security layer is NOT be negotiated using SASL). Conversely, if a security layer
to be negotiated via SASL, TLS MUST NOT be used. is to be negotiated via SASL, TLS MUST NOT be used.
5.2 Narrative 5.2 Narrative
When an initiating entity secures a stream with a receiving entity, When an initiating entity secures a stream with a receiving entity,
the steps involved are as follows: the steps involved are as follows:
1. Then initiating entity opens a TCP connection and initiates the 1. Then initiating entity opens a TCP connection and initiates the
stream by sending the opening XML stream header to the receiving stream by sending the opening XML stream header to the receiving
entity, including the "version='1.0'" flag. entity, including the "version='1.0'" flag.
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<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
<mechanism>EXTERNAL</mechanism> <mechanism>EXTERNAL</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 9: Client SHOULD continue with stream authentication (Section Step 9: Client SHOULD continue with stream authentication (Section
6). 6).
5.4 Server-to-Server Example 5.4 Server-to-Server Example
By bilateral agreement, server administrators MAY choose to use TLS By bilateral agreement, server administrators SHOULD choose to use
between two domains for the purpose of securing server-to-server TLS between two domains for the purpose of securing server-to-server
communications. communications.
The following example shows the data flow for two servers securing a The following example shows the data flow for two servers securing a
stream using STARTTLS. stream using STARTTLS.
Step 1: Server1 initiates stream to Server2: Step 1: Server1 initiates stream to Server2:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
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of XML streams. When one entity is already known to another (i.e., of XML streams. When one entity is already known to another (i.e.,
there is an existing trust relationship between the entities such as there is an existing trust relationship between the entities such as
that established when a user registers with a server or an that established when a user registers with a server or an
administrator configures a server to trust another server), the administrator configures a server to trust another server), the
preferred method for authenticating streams between the two entities preferred method for authenticating streams between the two entities
uses an XMPP adaptation of the Simple Authentication and Security uses an XMPP adaptation of the Simple Authentication and Security
Layer (SASL) [22]. When there is no existing trust relationship Layer (SASL) [22]. When there is no existing trust relationship
between two servers, some level of trust MAY be established based on between two servers, some level of trust MAY be established based on
existing trust in DNS; the authentication method used in this case is existing trust in DNS; the authentication method used in this case is
the server dialback protocol that is native to XMPP (no such ad-hoc the server dialback protocol that is native to XMPP (no such ad-hoc
method is defined between a client and a server). If SASL is used for method is defined between a client and a server). If SASL is used
server-to-server authentication, the servers MUST NOT use dialback. for server-to-server authentication, the servers MUST NOT use
Both SASL authentication and dialback are described in this section. dialback. Both SASL authentication and dialback are described in
this section.
Stream authentication is REQUIRED for all direct communications Stream authentication is REQUIRED for all direct communications
between two entities; if an entity sends a stanza to an between two entities; if an entity sends a stanza to an
unauthenticated stream, the receiving entity SHOULD silently drop the unauthenticated stream, the receiving entity SHOULD silently drop the
stanza and MUST NOT process it. stanza and MUST NOT process it.
6.1 SASL Authentication 6.1 SASL Authentication
6.1.1 Overview 6.1.1 Overview
The Simple Authentication and Security Layer (SASL) provides a The Simple Authentication and Security Layer (SASL) provides a
generalized method for adding authentication support to generalized method for adding authentication support to connection-
connection-based protocols. XMPP uses a generic XML namespace profile based protocols. XMPP uses a generic XML namespace profile for SASL
for SASL that conforms to section 4 ("Profiling Requirements") of RFC that conforms to section 4 ("Profiling Requirements") of RFC 2222
2222 [22] (the namespace identifier for this protocol is 'http:// [22] (the namespace identifier for this protocol is 'http://
www.iana.org/assignments/sasl-mechanisms'). www.iana.org/assignments/sasl-mechanisms').
The following rules MUST be observed: The following rules MUST be observed:
1. If TLS is used for stream encryption, SASL MUST NOT be used for 1. If TLS is used for stream encryption, SASL MUST NOT be used for
anything but stream authentication (i.e., a security layer MUST anything but stream authentication (i.e., a security layer MUST
NOT be negotiated using SASL). Conversely, if a security layer is NOT be negotiated using SASL). Conversely, if a security layer
to be negotiated via SASL, TLS MUST NOT be used. is to be negotiated via SASL, TLS MUST NOT be used.
2. If the initiating entity is capable of authenticating via SASL, 2. If the initiating entity is capable of authenticating via SASL,
it it MUST include the "version='1.0'" flag in the initiating it it MUST include the "version='1.0'" flag in the initiating
stream header. stream header.
3. If the receiving entity is capable of accepting authentications 3. If the receiving entity is capable of accepting authentications
via SASL, it MUST send one or more authentication mechanisms via SASL, it MUST send one or more authentication mechanisms
within a <mechanisms/> element in response to the opening stream within a <mechanisms/> element in response to the opening stream
tag received from the initiating entity. tag received from the initiating entity.
skipping to change at page 27, line 7 skipping to change at page 27, line 8
exchange sequence: Challenges and responses are carried through the exchange sequence: Challenges and responses are carried through the
exchange of <challenge/> elements from receiving entity to exchange of <challenge/> elements from receiving entity to
initiating entity and <response/> elements from initiating entity initiating entity and <response/> elements from initiating entity
to receiving entity. The receiving entity reports failure by to receiving entity. The receiving entity reports failure by
sending a <failure/> element and success by sending a <success/> sending a <failure/> element and success by sending a <success/>
element; the initiating entity aborts the exchange by sending an element; the initiating entity aborts the exchange by sending an
<abort/> element. <abort/> element.
security layer negotiation: If a security layer is negotiated, both security layer negotiation: If a security layer is negotiated, both
sides consider the original stream closed and new <stream/> sides consider the original stream closed and new <stream/>
headers are sent by both entities. The security layer takes effect headers are sent by both entities. The security layer takes
immediately following the ">" character of the empty <response/> effect immediately following the ">" character of the empty
element for the client and immediately following the closing ">" <response/> element for the client and immediately following the
character of the <succeed/> element for the server. closing ">" character of the <succeed/> element for the server.
use of the authorization identity: The authorization identity, if use of the authorization identity: The authorization identity, if
present, is unused by xmpp. present, is unused by xmpp.
6.1.4 Client-to-Server Example 6.1.4 Client-to-Server Example
The following example shows the data flow for a client authenticating The following example shows the data flow for a client authenticating
with a server using SASL. with a server using SASL.
Step 1: Client initiates stream to server: Step 1: Client initiates stream to server:
skipping to change at page 28, line 20 skipping to change at page 28, line 20
Step 5: Server sends a base64-encoded challenge to the client: Step 5: Server sends a base64-encoded challenge to the client:
<challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi
xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ qop="auth",charset=utf-
qop="auth",charset=utf-8,algorithm=md5-sess 8,algorithm=md5-sess
Step 6: Client responds to the challenge: Step 6: Client responds to the challenge:
<response xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <response xmlns='http://www.iana.org/assignments/sasl-mechanisms'>
dXNlcm5hbWU9InJvYiIscmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik dXNlcm5hbWU9InJvYiIscmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik
9BNk1HOXRFUUdtMmhoIixcIGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5j 9BNk1HOXRFUUdtMmhoIixcIGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5j
PTAwMDAwMDAxLHFvcD1hdXRoLFwgZGlnZXN0LXVyaT0ieG1wcC9jYXRhY2 PTAwMDAwMDAxLHFvcD1hdXRoLFwgZGlnZXN0LXVyaT0ieG1wcC9jYXRhY2
x5c20uY3giLFwgcmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZ x5c20uY3giLFwgcmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZ
jIxNDNhZjcsY2hhcnNldD11dGYtOA== jIxNDNhZjcsY2hhcnNldD11dGYtOA==
</response> </response>
skipping to change at page 30, line 38 skipping to change at page 30, line 38
Step 5: Server2 sends a base64-encoded challenge to Server1: Step 5: Server2 sends a base64-encoded challenge to Server1:
<challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi
xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ qop="auth",charset=utf-
qop="auth",charset=utf-8,algorithm=md5-sess 8,algorithm=md5-sess
Step 6: Server1 responds to the challenge: Step 6: Server1 responds to the challenge:
<response xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <response xmlns='http://www.iana.org/assignments/sasl-mechanisms'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixjbm9uY2U9Ik9B cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixjbm9uY2U9Ik9B
Nk1IWGg2VnFUclJrIixuYz0wMDAwMDAwMSxxb3A9YXV0aCxkaWdlc3QtdXJpPSJ4bXBwL2Nh Nk1IWGg2VnFUclJrIixuYz0wMDAwMDAwMSxxb3A9YXV0aCxkaWdlc3QtdXJpPSJ4bXBwL2Nh
dGFjbHlzbS5jeCIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcs dGFjbHlzbS5jeCIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcs
Y2hhcnNldD11dGYtOAo= Y2hhcnNldD11dGYtOAo=
</response> </response>
skipping to change at page 32, line 11 skipping to change at page 32, line 15
6.2 Dialback Authentication 6.2 Dialback Authentication
XMPP includes a protocol-level method for verifying that a connection XMPP includes a protocol-level method for verifying that a connection
between two servers can be trusted (at least as much as the DNS can between two servers can be trusted (at least as much as the DNS can
be trusted). The method is called dialback and is used only within be trusted). The method is called dialback and is used only within
XML streams that are declared under the "jabber:server" namespace. XML streams that are declared under the "jabber:server" namespace.
The purpose of the dialback protocol is to make server spoofing more The purpose of the dialback protocol is to make server spoofing more
difficult, and thus to make it more difficult to forge XML stanzas. difficult, and thus to make it more difficult to forge XML stanzas.
Dialback is not intended as a mechanism for securing or encrypting Dialback is not intended as a mechanism for securing or encrypting
the streams between servers, only for helping to prevent the spoofing the streams between servers as is done via SASL and TLS, only for
of a server and the sending of false data from it. Domains requiring helping to prevent the spoofing of a server and the sending of false
more robust security SHOULD use TLS or SASL as defined above. data from it. Domains requiring more robust security SHOULD use TLS
or SASL as defined above.
Server dialback is made possible by the existence of DNS, since one Server dialback is made possible by the existence of DNS, since one
server can verify that another server which is connecting to it is server can verify that another server which is connecting to it is
authorized to represent a given server on the Jabber network. All DNS authorized to represent a given server on the Jabber network. All
hostname resolutions MUST first resolve the hostname using an SRV DNS hostname resolutions MUST first resolve the hostname using an SRV
[24] record of _jabber._tcp.server. If the SRV lookup fails, the [24] record of _jabber._tcp.server. If the SRV lookup fails, the
fallback is a normal A lookup to determine the IP address, using the fallback is a normal A lookup to determine the IP address, using the
jabber-server port of 5269 assigned by the Internet Assigned Numbers jabber-server port of 5269 assigned by the Internet Assigned Numbers
Authority [7]. Authority [7].
Note: the method for generating and verifying the keys used in the Note: the method for generating and verifying the keys used in the
dialback protocol MUST take into account the hostnames being used, dialback protocol MUST take into account the hostnames being used,
along with a secret known only by the receiving server and the random along with a secret known only by the receiving server and the random
ID generated for the stream. Generating unique but verifiable keys is ID generated for the stream. Generating unique but verifiable keys
important to prevent common man-in-the-middle attacks and server is important to prevent common man-in-the-middle attacks and server
spoofing. spoofing.
In the description that follows we use the following terminology: In the description that follows we use the following terminology:
o Originating Server -- the server that is attempting to establish a o Originating Server -- the server that is attempting to establish a
connection between the two servers connection between the two servers
o Receiving Server -- the server that is trying to authenticate that o Receiving Server -- the server that is trying to authenticate that
Originating Server represents the Jabber server which it claims to Originating Server represents the Jabber server which it claims to
be be
skipping to change at page 37, line 17 skipping to change at page 37, line 17
7.1 Overview 7.1 Overview
Once the XML streams in each direction have been authenticated and Once the XML streams in each direction have been authenticated and
(if desired) encrypted, XML stanzas can be sent over the streams. (if desired) encrypted, XML stanzas can be sent over the streams.
Three XML stanza types are defined for the 'jabber:client' and Three XML stanza types are defined for the 'jabber:client' and
'jabber:server' namespaces: <message/>, <presence/>, and <iq/>. 'jabber:server' namespaces: <message/>, <presence/>, and <iq/>.
In essence, the <message/> stanza type can be seen as a "push" In essence, the <message/> stanza type can be seen as a "push"
mechanism whereby one entity pushes information to another entity, mechanism whereby one entity pushes information to another entity,
similar to the communications that occur in a system such as email. similar to the communications that occur in a system such as email.
The <presence/> element can be seen as a basic broadcast or The <presence/> element can be seen as a basic broadcast or "publish-
"publish-subscribe" mechanism, whereby multiple entities receive subscribe" mechanism, whereby multiple entities receive information
information (in this case, presence information) about an entity to (in this case, presence information) about an entity to which they
which they have subscribed. The <iq/> element can be seen as a have subscribed. The <iq/> element can be seen as a "request-
"request-response" mechanism similar to HTTP, whereby two entities response" mechanism similar to HTTP, whereby two entities can engage
can engage in a structured conversation using 'get' or 'set' requests in a structured conversation using 'get' or 'set' requests and
and 'result' or 'error' responses. 'result' or 'error' responses.
The syntax for these stanza types is defined below. The syntax for these stanza types is defined below.
7.2 Common Attributes 7.2 Common Attributes
Five attributes are common to message, presence, and IQ stanzas. Five attributes are common to message, presence, and IQ stanzas.
These are defined below. These are defined below.
7.2.1 to 7.2.1 to
The 'to' attribute specifies the JID of the intended recipient for The 'to' attribute specifies the JID of the intended recipient for
the stanza. In the 'jabber:client' namespace, a stanza SHOULD possess the stanza. In the 'jabber:client' namespace, a stanza SHOULD
a 'to' attribute, although a stanza sent from a client to a server possess a 'to' attribute, although a stanza sent from a client to a
for handling by that server (e.g., presence sent to the server for server for handling by that server (e.g., presence sent to the server
broadcasting to other entities) MAY legitimately lack a 'to' for broadcasting to other entities) MAY legitimately lack a 'to'
attribute. In the 'jabber:server' namespace, a stanza MUST possess a attribute. In the 'jabber:server' namespace, a stanza MUST possess a
'to' attribute. 'to' attribute.
7.2.2 from 7.2.2 from
The 'from' attribute specifies the JID of the sender. The 'from' attribute specifies the JID of the sender.
In the 'jabber:client' namespace, a client MUST NOT include a 'from' In the 'jabber:client' namespace, a client MUST NOT include a 'from'
attribute on the stanzas it sends to a server; if a server receives a attribute on the stanzas it sends to a server; if a server receives a
stanza from a client and the stanza possesses a 'from' attribute, it stanza from a client and the stanza possesses a 'from' attribute, it
MUST ignore the value of the 'from' attribute and MAY return an error MUST ignore the value of the 'from' attribute and MAY return an error
to the sender. In addition, a server MUST stamp stanzas received from to the sender. In addition, a server MUST stamp stanzas received
a client with the user@domain/resource (full JID) of the connected from a client with the user@domain/resource (full JID) of the
resource that generated the stanza. connected resource that generated the stanza.
In the 'jabber:server' namespace, a stanza MUST possess a 'from' In the 'jabber:server' namespace, a stanza MUST possess a 'from'
attribute. In particular, a server MUST include a 'from' attribute on attribute. In particular, a server MUST include a 'from' attribute
stanzas it routes to other servers. The domain identifier of the JID on stanzas it routes to other servers. The domain identifier of the
contained in the 'from' attribute MUST match the hostname of the JID contained in the 'from' attribute MUST match the hostname of the
server (or a subdomain thereof) as communicated in the SASL server (or a subdomain thereof) as communicated in the SASL
negotiation or dialback negotiation. negotiation or dialback negotiation.
7.2.3 id 7.2.3 id
The optional 'id' attribute MAY be used to track stanzas sent and The optional 'id' attribute MAY be used to track stanzas sent and
received. The 'id' attribute is generated by the sender. An 'id' received. The 'id' attribute is generated by the sender. An 'id'
attribute included in an IQ request of type "get" or "set" SHOULD be attribute included in an IQ request of type "get" or "set" SHOULD be
returned to the sender in any IQ response of type "result" or "error" returned to the sender in any IQ response of type "result" or "error"
generated by the recipient of the request. A recipient of a message generated by the recipient of the request. A recipient of a message
skipping to change at page 39, line 8 skipping to change at page 39, line 8
Message stanzas in the 'jabber:client' or 'jabber:server' namespace Message stanzas in the 'jabber:client' or 'jabber:server' namespace
are used to "push" information to another entity. Common uses in the are used to "push" information to another entity. Common uses in the
context of instant messaging include single messages, messages sent context of instant messaging include single messages, messages sent
in the context of a chat conversation, messages sent in the context in the context of a chat conversation, messages sent in the context
of a multi-user chat room, headlines, and errors. These messages of a multi-user chat room, headlines, and errors. These messages
types are identified more fully below. types are identified more fully below.
7.3.1 Types of Message 7.3.1 Types of Message
The 'type' attribute of a message stanza is OPTIONAL; if included, it The 'type' attribute of a message stanza is OPTIONAL; if included, it
specifies the conversational context of the message. The sending of a specifies the conversational context of the message. The sending of
message stanza without a 'type' attribute signals that the message a message stanza without a 'type' attribute signals that the message
stanza is a single message. However, the 'type' attribute MAY also stanza is a single message. However, the 'type' attribute MAY also
have one of the following values: have one of the following values:
o chat o chat
o error o error
o groupchat o groupchat
o headline o headline
skipping to change at page 39, line 36 skipping to change at page 39, line 36
As described under extended namespaces (Section 7.6), a message As described under extended namespaces (Section 7.6), a message
stanza MAY contain any properly-namespaced child element as long as stanza MAY contain any properly-namespaced child element as long as
the namespace name is not "jabber:client", "jabber:server", or the namespace name is not "jabber:client", "jabber:server", or
"http://etherx.jabber.org/streams", and as long as the element name "http://etherx.jabber.org/streams", and as long as the element name
does not match that of one of the core data elements, stream does not match that of one of the core data elements, stream
elements, or defined children thereof. elements, or defined children thereof.
In accordance with the default namespace declaration, by default a In accordance with the default namespace declaration, by default a
message stanza is in the 'jabber:client' or 'jabber:server' message stanza is in the 'jabber:client' or 'jabber:server'
namespace, which defines certain allowable children of message namespace, which defines certain allowable children of message
stanzas. If the message stanza is of type "error", it MUST include an stanzas. If the message stanza is of type "error", it MUST include
<error/> child; for details, see Section 7.7. If the message stanza an <error/> child; for details, see Section 7.7. If the message
has no 'type' attribute or has a 'type' attribute with a value of stanza has no 'type' attribute or has a 'type' attribute with a value
"chat", "groupchat", or "headline", it MAY contain any of the of "chat", "groupchat", or "headline", it MAY contain any of the
following child elements without an explicit namespace declaration: following child elements without an explicit namespace declaration:
7.3.2.1 Body 7.3.2.1 Body
The <body/> element contains the textual contents of the message; The <body/> element contains the textual contents of the message;
normally included but NOT REQUIRED. The <body/> element MUST NOT normally included but NOT REQUIRED. The <body/> element MUST NOT
possess any attributes, with the exception of the 'xml:lang' possess any attributes, with the exception of the 'xml:lang'
attribute. Multiple instances of the <body/> element MAY be included attribute. Multiple instances of the <body/> element MAY be included
but only if each instance possesses an 'xml:lang' attribute with a but only if each instance possesses an 'xml:lang' attribute with a
distinct language value. The <body> element MUST NOT contain mixed distinct language value. The <body> element MUST NOT contain mixed
content. content.
7.3.2.2 Subject 7.3.2.2 Subject
The <subject/> element specifies the topic of the message. The The <subject/> element specifies the topic of the message. The
<subject/> element MUST NOT possess any attributes, with the <subject/> element MUST NOT possess any attributes, with the
exception of the 'xml:lang' attribute. Multiple instances of the exception of the 'xml:lang' attribute. Multiple instances of the
<subject/> element MAY be included for the purpose of providing <subject/> element MAY be included for the purpose of providing
alternate versions of the same subject, but only if each instance alternate versions of the same subject, but only if each instance
possesses an 'xml:lang' attribute with a distinct language value. The possesses an 'xml:lang' attribute with a distinct language value.
<subject> element MUST NOT contain mixed content. The <subject> element MUST NOT contain mixed content.
7.3.2.3 Thread 7.3.2.3 Thread
The <thread/> element contains a random string that is generated by The <thread/> element contains a random string that is generated by
the sender and that SHOULD be copied back in replies; it is used for the sender and that SHOULD be copied back in replies; it is used for
tracking a conversation thread (sometimes referred to as an "IM tracking a conversation thread (sometimes referred to as an "IM
session") between two entities. If used, it MUST be unique to that session") between two entities. If used, it MUST be unique to that
conversation thread within the stream and MUST be consistent conversation thread within the stream and MUST be consistent
throughout that conversation. The use of the <thread/> element is throughout that conversation. The use of the <thread/> element is
optional and is not used to identify individual messages, only optional and is not used to identify individual messages, only
conversations. Only one <thread/> element MAY be included in a conversations. Only one <thread/> element MAY be included in a
message stanza, and it MUST NOT possess any attributes. The <thread/> message stanza, and it MUST NOT possess any attributes. The <thread/
element MUST be treated as an opaque string by entities; no semantic > element MUST be treated as an opaque string by entities; no
meaning may be derived from it, and only exact, case-insensitve semantic meaning may be derived from it, and only exact, case-
comparisons be made against it. The <thread> element MUST NOT contain insensitve comparisons be made against it. The <thread> element MUST
mixed content. NOT contain mixed content.
The method for generating thread IDs SHOULD be as follows: The method for generating thread IDs SHOULD be as follows:
1. concatenate the sender's full JID (user@host/resource) with the 1. concatenate the sender's full JID (user@host/resource) with the
recipient's full JID recipient's full JID
2. concatenate these JID strings with a full ISO-8601 timestamp 2. concatenate these JID strings with a full ISO-8601 timestamp
including year, month, day, hours, minutes, seconds, and UTC including year, month, day, hours, minutes, seconds, and UTC
offset in the following format: yyyy-mm-dd-Thh:mm:ss-hh:mm offset in the following format: yyyy-mm-dd-Thh:mm:ss-hh:mm
skipping to change at page 42, line 13 skipping to change at page 42, line 13
stanzas. If the presence stanza is of type "error", it MUST include stanzas. If the presence stanza is of type "error", it MUST include
an <error/> child; for details, see Section 7.7. If the presence an <error/> child; for details, see Section 7.7. If the presence
stanza possesses no 'type' attribute, it MAY contain any of the stanza possesses no 'type' attribute, it MAY contain any of the
following child elements (note that the <status/> child MAY be sent following child elements (note that the <status/> child MAY be sent
in a presence stanza of type "unavailable" or, for historical in a presence stanza of type "unavailable" or, for historical
reasons, "subscribe"): reasons, "subscribe"):
7.4.2.1 Show 7.4.2.1 Show
The <show/> element specifies describes the availability status of an The <show/> element specifies describes the availability status of an
entity or specific resource. Only one <show/> element MAY be included entity or specific resource. Only one <show/> element MAY be
in a presence stanza, and it MUST NOT possess any attributes. The included in a presence stanza, and it MUST NOT possess any
value SHOULD be one of the following (values other than these four attributes. The value SHOULD be one of the following (values other
MAY be ignored; additional availability types could be defined than these four MAY be ignored; additional availability types could
through a properly-namespaced child element of the presence stanza): be defined through a properly-namespaced child element of the
presence stanza):
o away o away
o chat o chat
o xa o xa
o dnd o dnd
For information about the meaning of these values, refer to XMPP IM For information about the meaning of these values, refer to XMPP IM
[3]. [3].
7.4.2.2 Status 7.4.2.2 Status
The optional <status/> element specifies a natural-language The optional <status/> element specifies a natural-language
description of availability status. It is normally used in description of availability status. It is normally used in
conjunction with the show element to provide a detailed description conjunction with the show element to provide a detailed description
of an availability state (e.g., "In a meeting"). The <status/> of an availability state (e.g., "In a meeting"). The <status/>
element MUST NOT possess any attributes, with the exception of the element MUST NOT possess any attributes, with the exception of the
'xml:lang' attribute. Multiple instances of the <status/> element MAY 'xml:lang' attribute. Multiple instances of the <status/> element
be included but only if each instance possesses an 'xml:lang' MAY be included but only if each instance possesses an 'xml:lang'
attribute with a distinct language value. attribute with a distinct language value.
7.4.2.3 Priority 7.4.2.3 Priority
The optional <priority/> element specifies the priority level of the The optional <priority/> element specifies the priority level of the
connected resource. The value may be any integer between -128 to 127. connected resource. The value may be any integer between -128 to
Only one <priority/> element MAY be included in a presence stanza, 127. Only one <priority/> element MAY be included in a presence
and it MUST NOT possess any attributes. For information regarding the stanza, and it MUST NOT possess any attributes. For information
use of priority values in stanza routing within IM applications, see regarding the use of priority values in stanza routing within IM
XMPP IM [3]. applications, see XMPP IM [3].
7.5 IQ Stanzas 7.5 IQ Stanzas
7.5.1 Overview 7.5.1 Overview
Info/Query, or IQ, is a request-response mechanism, similar in some Info/Query, or IQ, is a request-response mechanism, similar in some
ways to HTTP [25]. IQ stanzas in the 'jabber:client' or ways to HTTP [25]. IQ stanzas in the 'jabber:client' or
'jabber:server' namespace enable an entity to make a request of, and 'jabber:server' namespace enable an entity to make a request of, and
receive a response from, another entity. The data content of the receive a response from, another entity. The data content of the
request and response is defined by the namespace declaration of a request and response is defined by the namespace declaration of a
skipping to change at page 43, line 39 skipping to change at page 43, line 41
| | | |
| <iq type='set' id='2'> | | <iq type='set' id='2'> |
| ------------------------> | | ------------------------> |
| | | |
| <iq type='result' id='2'> | | <iq type='result' id='2'> |
| <------------------------ | | <------------------------ |
| | | |
An entity that receives an IQ request of type 'get' or 'set' MUST An entity that receives an IQ request of type 'get' or 'set' MUST
reply with an IQ response of type 'result' or 'error' (which response reply with an IQ response of type 'result' or 'error' (which response
SHOULD preserve the 'id' attribute of the request). An entity that MUST preserve the 'id' attribute of the request). An entity that
receives a stanza of type 'result' or 'error' MUST NOT respond to the receives a stanza of type 'result' or 'error' MUST NOT respond to the
stanza by sending a further IQ response of type 'result' or 'error'; stanza by sending a further IQ response of type 'result' or 'error';
however, as shown above, the requesting entity MAY send another however, as shown above, the requesting entity MAY send another
request (e.g., an IQ of type 'set' in order to provide required request (e.g., an IQ of type 'set' in order to provide required
information discovered through a get/result pair). information discovered through a get/result pair).
7.5.2 Types of IQ 7.5.2 Types of IQ
The 'type' attribute of an IQ stanza is REQUIRED. The 'type' The 'type' attribute of an IQ stanza is REQUIRED. The 'type'
attribute specifies a distinct step within a request-response attribute specifies a distinct step within a request-response
skipping to change at page 44, line 39 skipping to change at page 44, line 40
7.6 Extended Namespaces 7.6 Extended Namespaces
While the core data elements in the "jabber:client" or While the core data elements in the "jabber:client" or
"jabber:server" namespace (along with their attributes and child "jabber:server" namespace (along with their attributes and child
elements) provide a basic level of functionality for messaging and elements) provide a basic level of functionality for messaging and
presence, XMPP uses XML namespaces to extend the core data elements presence, XMPP uses XML namespaces to extend the core data elements
for the purpose of providing additional functionality. Thus a for the purpose of providing additional functionality. Thus a
message, presence, or IQ stanza MAY house one or more optional child message, presence, or IQ stanza MAY house one or more optional child
elements containing content that extends the meaning of the message elements containing content that extends the meaning of the message
(e.g., an encrypted form of the message body). This child element MAY (e.g., an encrypted form of the message body). This child element
be any element (other than the core data elements, stream elements, MAY be any element (other than the core data elements, stream
or defined children thereof). The child element MUST possess an elements, or defined children thereof). The child element MUST
'xmlns' namespace declaration (other than the stream namespace and possess an 'xmlns' namespace declaration (other than the stream
the default namespace) that defines all data contained within the namespace and the default namespace) that defines all data contained
child element. within the child element.
Support for any given extended namespace is OPTIONAL on the part of Support for any given extended namespace is OPTIONAL on the part of
any implementation. If an entity does not understand such a any implementation. If an entity does not understand such a
namespace, it MUST ignore the associated XML data (if the stanza is namespace, it MUST ignore the associated XML data (if the stanza is
being routed on to another entity, ignore means "pass it on being routed on to another entity, ignore means "pass it on
untouched"). If an entity receives a message or presence stanza that untouched"). If an entity receives a message or presence stanza that
contains XML data in an extended namespace it does not understand, contains XML data in an extended namespace it does not understand,
the portion of the stanza that is in the unknown namespace SHOULD be the portion of the stanza that is in the unknown namespace SHOULD be
ignored. If an entity receives a message stanza without a <body/> ignored. If an entity receives a message stanza without a <body/>
element but containing only a child element bound by a namespace it element but containing only a child element bound by a namespace it
skipping to change at page 46, line 12 skipping to change at page 46, line 14
The value of the 'class' attribute must be one of the following: The value of the 'class' attribute must be one of the following:
o access -- the condition relates to access rights, permissions, or o access -- the condition relates to access rights, permissions, or
authorization authorization
o address -- the condition relates to the JID or domain to which the o address -- the condition relates to the JID or domain to which the
stanza was addressed stanza was addressed
o app -- the condition is particular to an application and is o app -- the condition is particular to an application and is
specified in a namespace other than specified in a namespace other than 'urn:ietf:rfc:xmppcore-rfc-
'urn:ietf:rfc:xmppcore-rfc-number:stanzas' number:stanzas'
o format -- the condition relates to XML format or structure o format -- the condition relates to XML format or structure
o recipient -- the condition relates to the state or capabilities of o recipient -- the condition relates to the state or capabilities of
the recipient (which may be the server) the recipient (which may be the server)
o server -- the condition relates to the internal state of the o server -- the condition relates to the internal state of the
server server
The <stanza-condition/> element MUST contain a child element that The <stanza-condition/> element MUST contain a child element that
specifies a particular stanza-related error condition, as defined in specifies a particular stanza-related error condition, as defined in
the next section. (Note: the XML namespace name the next section. (Note: the XML namespace name
'urn:ietf:rfc:xmppcore-rfc-number:stanzas' that scopes the 'urn:ietf:rfc:xmppcore-rfc-number:stanzas' that scopes the <stanza-
<stanza-condition/> element adheres to the format defined in RFC 2648 condition/> element adheres to the format defined in RFC 2648 [16].)
[16].)
7.7.3 Conditions 7.7.3 Conditions
The following stanza-related error conditions are defined: The following stanza-related error conditions are defined:
o <bad-request/> -- the sender has sent XML that is malformed or o <bad-request/> -- the sender has sent XML that is malformed or
cannot be processed (e.g., a client-generated stanza includes a cannot be processed (e.g., a client-generated stanza includes a
'from' address, or an IQ stanza includes an unrecognized value of 'from' address, or an IQ stanza includes an unrecognized value of
the 'type' attribute); the associated class is "format". the 'type' attribute); the associated class is "format".
skipping to change at page 47, line 34 skipping to change at page 47, line 35
as part or all of the JID of the intended recipient could not be as part or all of the JID of the intended recipient could not be
contacted within a reasonable amount of time; the associated class contacted within a reasonable amount of time; the associated class
is "server". is "server".
o <service-unavailable/> -- the service requested is currently o <service-unavailable/> -- the service requested is currently
unavailable on the server; the associated class is "server". unavailable on the server; the associated class is "server".
7.7.4 Extensibility 7.7.4 Extensibility
If desired, an XMPP application MAY provide custom error information; If desired, an XMPP application MAY provide custom error information;
this MUST be contained in a properly-namespaced child of the this MUST be contained in a properly-namespaced child of the <stanza-
<stanza-condition/> element (i.e., the namespace name MUST NOT be one condition/> element (i.e., the namespace name MUST NOT be one of
of namespace names defined herein). namespace names defined herein).
8. XML Usage within XMPP 8. XML Usage within XMPP
8.1 Namespaces 8.1 Namespaces
XML Namespaces [15] are used within all XMPP-compliant XML to create XML Namespaces [15] are used within all XMPP-compliant XML to create
strict boundaries of data ownership. The basic function of namespaces strict boundaries of data ownership. The basic function of
is to separate different vocabularies of XML elements that are namespaces is to separate different vocabularies of XML elements that
structurally mixed together. Ensuring that XMPP-compliant XML is are structurally mixed together. Ensuring that XMPP-compliant XML is
namespace-aware enables any XML to be structurally mixed with any namespace-aware enables any XML to be structurally mixed with any
data element within XMPP. data element within XMPP.
Additionally, XMPP is more strict about namespace prefixes than the Additionally, XMPP is more strict about namespace prefixes than the
XML namespace specification requires. XML namespace specification requires.
8.2 Validation 8.2 Validation
A server is not responsible for validating the XML elements forwarded A server is not responsible for validating the XML elements forwarded
to a client or another server; an implementation MAY choose to to a client or another server; an implementation MAY choose to
skipping to change at page 48, line 35 skipping to change at page 48, line 35
conform to the schemas, and SHOULD ignore any non-conformant elements conform to the schemas, and SHOULD ignore any non-conformant elements
or attributes on the incoming XML stream. Validation of XML streams or attributes on the incoming XML stream. Validation of XML streams
and stanzas is NOT REQUIRED or recommended, and schemas are included and stanzas is NOT REQUIRED or recommended, and schemas are included
herein for descriptive purposes only. herein for descriptive purposes only.
8.3 Character Encodings 8.3 Character Encodings
Software implementing XML streams MUST support the UTF-8 (RFC 2279 Software implementing XML streams MUST support the UTF-8 (RFC 2279
[26]) and UTF-16 (RFC 2781 [27]) transformations of Universal [26]) and UTF-16 (RFC 2781 [27]) transformations of Universal
Character Set (ISO/IEC 10646-1 [28]) characters. Software MUST NOT Character Set (ISO/IEC 10646-1 [28]) characters. Software MUST NOT
attempt to use any other encoding for transmitted data. The encodings attempt to use any other encoding for transmitted data. The
of the transmitted and received streams are independent. Software MAY encodings of the transmitted and received streams are independent.
select either UTF-8 or UTF-16 for the transmitted stream, and SHOULD Software MAY select either UTF-8 or UTF-16 for the transmitted
deduce the encoding of the received stream as described in the XML stream, and SHOULD deduce the encoding of the received stream as
specification [1]. For historical reasons, existing implementations described in the XML specification [1]. For historical reasons,
MAY support UTF-8 only. existing implementations MAY support UTF-8 only.
8.4 Inclusion of Text Declaration 8.4 Inclusion of Text Declaration
An application MAY send a text declaration. Applications MUST follow An application MAY send a text declaration. Applications MUST follow
the rules in the XML specification [1] regarding the circumstances the rules in the XML specification [1] regarding the circumstances
under which a text declaration is included. under which a text declaration is included.
9. IANA Considerations 9. IANA Considerations
The IANA registers "xmpp" as a GSSAPI [30] service name, as specified The IANA registers "xmpp" as a GSSAPI [30] service name, as specified
skipping to change at page 51, line 7 skipping to change at page 51, line 7
as keywords for TCP ports 5222 and 5269 respectively. as keywords for TCP ports 5222 and 5269 respectively.
10. Internationalization Considerations 10. Internationalization Considerations
Usage of the 'xml:lang' attribute is described above. If a client Usage of the 'xml:lang' attribute is described above. If a client
includes an 'xml:lang' attribute in a stanza, the server MUST NOT includes an 'xml:lang' attribute in a stanza, the server MUST NOT
modify or delete it. modify or delete it.
11. Security Considerations 11. Security Considerations
11.1 Client-to-Server Communications 11.1 High Security
For the purposes of XMPP communications (client-to-server and server-
to-server), the term "high security" refers to the use of security
technologies that provide both mutual authentication and integrity-
checking; in particular, when using certificate-based authentication
to provide high security, a chain-of-trust must be established out-
of-band (i.e., no self-signed certificates).
Implementations MUST support high security. Service provisioning
SHOULD use high security, subject to local security policies.
11.2 Client-to-Server Communications
The TLS protocol for encrypting XML streams (defined under Section 5) The TLS protocol for encrypting XML streams (defined under Section 5)
provides a reliable mechanism for helping to ensure the privacy and provides a reliable mechanism for helping to ensure the
data integrity of data exchanged between two entities. confidentiality and data integrity of data exchanged between two
entities.
The SASL protocol for authenticating XML streams (defined under The SASL protocol for authenticating XML streams (defined under
Section 6.1) provides a reliable mechanism for validating that a Section 6.1) provides a reliable mechanism for validating that a
client connecting to a server is who it claims to be. client connecting to a server is who it claims to be.
The IP address and method of access of clients MUST NOT be made The IP address and method of access of clients MUST NOT be made
available by a server, nor are any connections other than the available by a server, nor are any connections other than the
original server connection required. This helps protect the client's original server connection required. This helps protect the client's
server from direct attack or identification by third parties. server from direct attack or identification by third parties.
End-to-end encryption of message bodies and presence status End-to-end encryption of message bodies and presence status
information MAY be effected through use of the methods defined in information MAY be effected through use of the methods defined in
End-to-End Object Encryption in XMPP [29]. End-to-End Object Encryption in XMPP [29].
11.2 Server-to-Server Communications 11.3 Server-to-Server Communications
It is OPTIONAL for any given server to communicate with other A compliant implementation MUST support both TLS and SASL for inter-
servers, and server-to-server communications MAY be disabled by the domain communications. For historical reasons, a compliant
administrator of any given deployment. implementation SHOULD also support the lower-security Dialback
Protocol (Section 6.2), which provides a mechanism for helping to
prevent the spoofing of domains.
If two servers would like to enable communications between Because service provisioning is a matter of policy, it is OPTIONAL
themselves, they MUST form a relationship of trust at some level, for any given domain to communicate with other domains, and server-
either based on trust in DNS or based on a pre-existing trust to-server communications MAY be disabled by the administrator of any
relationship (e.g., through exchange of certificates). If two servers given deployment. If a particular domain enables inter-domain
have a pre-existing trust relationship, they MAY use SASL communications, it SHOULD enable high security. In the absence of
Authentication (Section 6.1) for the purpose of authenticating each high security, a domain MAY use server dialback for inter-domain
other. If they do not have a pre-existing relationship, they MUST use communications.
the Dialback Protocol (Section 6.2), which provides a reliable
mechanism for preventing the spoofing of servers.
11.3 Firewalls 11.4 Firewalls
Communications using XMPP normally occur over TCP sockets on port Communications using XMPP normally occur over TCP sockets on port
5222 (client-to-server) or port 5269 (server-to-server), as 5222 (client-to-server) or port 5269 (server-to-server), as
registered with the IANA [7]. Use of these well-known ports allows registered with the IANA [7]. Use of these well-known ports allows
administrators to easily enable or disable XMPP activity through administrators to easily enable or disable XMPP activity through
existing and commonly-deployed firewalls. existing and commonly-deployed firewalls.
11.4 Minimum Security Mechanisms 11.5 Mandatory to Implement Technologies
Although service provisioning is a policy matter, at a minimum, all At a minimum, all implementations MUST support the following
implementations MUST support the following mechanisms: mechanisms:
for authentication: the SASL DIGEST-MD5 mechanism for authentication: the SASL DIGEST-MD5 mechanism
for confidentiality: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA for confidentiality: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA
cipher) cipher)
for both: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher for both: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher
supporting client-side certificates) supporting client-side certificates)
References References
[1] World Wide Web Consortium, "Extensible Markup Language (XML) [1] World Wide Web Consortium, "Extensible Markup Language (XML)
1.0 (Second Edition)", W3C xml, October 2000, <http:// 1.0 (Second Edition)", W3C xml, October 2000, <http://
www.w3.org/TR/2000/REC-xml-20001006>. www.w3.org/TR/2000/REC-xml-20001006>.
[2] Jabber Software Foundation, "Jabber Software Foundation", [2] Jabber Software Foundation, "Jabber Software Foundation",
August 2001, <http://www.jabber.org/>. August 2001, <http://www.jabber.org/>.
[3] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging [3] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging (draft-
(draft-ietf-xmpp-im-05, work in progress)", March 2003. ietf-xmpp-im-06, work in progress)", March 2003.
[4] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for [4] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for
Presence and Instant Messaging", RFC 2779, February 2000, Presence and Instant Messaging", RFC 2779, February 2000,
<http://www.ietf.org/rfc/rfc2779.txt>. <http://www.ietf.org/rfc/rfc2779.txt>.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[6] University of Southern California, "Transmission Control [6] University of Southern California, "Transmission Control
Protocol", RFC 793, September 1981, <http://www.ietf.org/rfc/ Protocol", RFC 793, September 1981, <http://www.ietf.org/rfc/
skipping to change at page 53, line 49 skipping to change at page 53, line 49
Support", STD 3, RFC 1123, October 1989. Support", STD 3, RFC 1123, October 1989.
[11] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile [11] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile
for Internationalized Domain Names (draft-ietf-idn-nameprep-11, for Internationalized Domain Names (draft-ietf-idn-nameprep-11,
work in progress)", June 2002. work in progress)", June 2002.
[12] Hoffman, P. and M. Blanchet, "Preparation of Internationalized [12] Hoffman, P. and M. Blanchet, "Preparation of Internationalized
Strings ("stringprep")", RFC 3454, December 2002. Strings ("stringprep")", RFC 3454, December 2002.
[13] Saint-Andre, P. and J. Hildebrand, "Nodeprep: A Stringprep [13] Saint-Andre, P. and J. Hildebrand, "Nodeprep: A Stringprep
Profile for Node Identifiers in XMPP Profile for Node Identifiers in XMPP (draft-ietf-xmpp-nodeprep-
(draft-ietf-xmpp-nodeprep-01, work in progress)", February 01, work in progress)", February 2003.
2003.
[14] Saint-Andre, P. and J. Hildebrand, "Resourceprep: A Stringprep [14] Saint-Andre, P. and J. Hildebrand, "Resourceprep: A Stringprep
Profile for Resource Identifiers in XMPP Profile for Resource Identifiers in XMPP (draft-ietf-xmpp-
(draft-ietf-xmpp-resourceprep-01, work in progress)", February resourceprep-01, work in progress)", February 2003.
2003.
[15] World Wide Web Consortium, "Namespaces in XML", W3C xml-names, [15] World Wide Web Consortium, "Namespaces in XML", W3C xml-names,
January 1999, <http://www.w3.org/TR/1999/ January 1999, <http://www.w3.org/TR/1999/REC-xml-names-
REC-xml-names-19990114/>. 19990114/>.
[16] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, [16] Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
August 1999. August 1999.
[17] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and [17] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and
P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January
1999. 1999.
[18] Crispin, M., "Internet Message Access Protocol - Version [18] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 2060, December 1996. 4rev1", RFC 2060, December 1996.
skipping to change at page 66, line 20 skipping to change at page 66, line 20
<xs:element name='stream-condition'> <xs:element name='stream-condition'>
<xs:complexType> <xs:complexType>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='1'/> maxOccurs='1'/>
<xs:choice maxOccurs='1'> <xs:choice maxOccurs='1'>
<xs:element ref='host-gone'/> <xs:element ref='host-gone'/>
<xs:element ref='host-unknown'/> <xs:element ref='host-unknown'/>
<xs:element ref='internal-server-error'/> <xs:element ref='internal-server-error'/>
<xs:element ref='invalid-namespace'/>
<xs:element ref='resource-constraint'/> <xs:element ref='resource-constraint'/>
<xs:element ref='see-other-host'/> <xs:element ref='see-other-host'/>
<xs:element ref='system-shutdown'/> <xs:element ref='system-shutdown'/>
<xs:element ref='unsupported-stanza-type'/> <xs:element ref='unsupported-stanza-type'/>
<xs:element ref='unsupported-version'/> <xs:element ref='unsupported-version'/>
<xs:element ref='xml-not-well-formed'/> <xs:element ref='xml-not-well-formed'/>
</xs:choice> </xs:choice>
</xs:complexType> </xs:complexType>
<xs:element name='host-gone' type='xs:string'/> <xs:element name='host-gone' type='xs:string'/>
<xs:element name='host-unknown' type='xs:string'/> <xs:element name='host-unknown' type='xs:string'/>
<xs:element name='internal-server-error' type='xs:string'/> <xs:element name='internal-server-error' type='xs:string'/>
<xs:element name='invalid-namespace' type='xs:string'/>
<xs:element name='resource-constraint' type='xs:string'/> <xs:element name='resource-constraint' type='xs:string'/>
<xs:element name='see-other-host' type='xs:string'/> <xs:element name='see-other-host' type='xs:string'/>
<xs:element name='system-shutdown' type='xs:string'/> <xs:element name='system-shutdown' type='xs:string'/>
<xs:element name='unsupported-stanza-type' type='xs:string'/> <xs:element name='unsupported-stanza-type' type='xs:string'/>
<xs:element name='unsupported-version' type='xs:string'/> <xs:element name='unsupported-version' type='xs:string'/>
<xs:element name='xml-not-well-formed' type='xs:string'/> <xs:element name='xml-not-well-formed' type='xs:string'/>
</xs:schema> </xs:schema>
A.8 Stanza error namespace A.8 Stanza error namespace
skipping to change at page 68, line 7 skipping to change at page 68, line 7
<xs:element name='recipient-unavailable' type='xs:string'/> <xs:element name='recipient-unavailable' type='xs:string'/>
<xs:element name='registration-required' type='xs:string'/> <xs:element name='registration-required' type='xs:string'/>
<xs:element name='remote-server-not-found' type='xs:string'/> <xs:element name='remote-server-not-found' type='xs:string'/>
<xs:element name='remote-server-timeout' type='xs:string'/> <xs:element name='remote-server-timeout' type='xs:string'/>
<xs:element name='service-unavailable' type='xs:string'/> <xs:element name='service-unavailable' type='xs:string'/>
</xs:schema> </xs:schema>
Appendix B. Provisional Namespace Names Appendix B. Provisional Namespace Names
Note to RFC editor: prior to publication, the string Note to RFC editor: prior to publication, the string 'xmppcore-rfc-
'xmppcore-rfc-number' must be replaced in all instances by the RFC number' must be replaced in all instances by the RFC number assigned
number assigned to this draft. (In addition, please remove this to this draft. (In addition, please remove this appendix, and the
appendix, and the corresponding entry in the table of contents, prior corresponding entry in the table of contents, prior to publication.)
to publication.)
Appendix C. Revision History Appendix C. Revision History
Note to RFC editor: please remove this entire appendix, and the Note to RFC editor: please remove this entire appendix, and the
corresponding entries in the table of contents, prior to publication. corresponding entries in the table of contents, prior to publication.
C.1 Changes from draft-ietf-xmpp-core-04 C.1 Changes from draft-ietf-xmpp-core-05
o Added <invalid-namespace/> as a stream error condition.
o Adjusted security considerations per discussion at IETF 56 and on
list.
C.2 Changes from draft-ietf-xmpp-core-04
o Added server-to-server examples for TLS and SASL. o Added server-to-server examples for TLS and SASL.
o Changed error syntax, rules, and examples based on list o Changed error syntax, rules, and examples based on list
discussion. discussion.
o Added schemas for the TLS, stream error, and stanza error o Added schemas for the TLS, stream error, and stanza error
namespaces. namespaces.
o Added note to RFC editor regarding provisional namespace names. o Added note to RFC editor regarding provisional namespace names.
o Made numerous small editorial changes and clarified text o Made numerous small editorial changes and clarified text
throughout. throughout.
C.2 Changes from draft-ietf-xmpp-core-03 C.3 Changes from draft-ietf-xmpp-core-03
o Clarified rules and procedures for TLS and SASL. o Clarified rules and procedures for TLS and SASL.
o Amplified stream error code syntax per list discussion. o Amplified stream error code syntax per list discussion.
o Made numerous small editorial changes. o Made numerous small editorial changes.
C.3 Changes from draft-ietf-xmpp-core-02 C.4 Changes from draft-ietf-xmpp-core-02
o Added dialback schema. o Added dialback schema.
o Removed all DTDs since schemas provide more complete definitions. o Removed all DTDs since schemas provide more complete definitions.
o Added stream error codes. o Added stream error codes.
o Clarified error code "philosophy". o Clarified error code "philosophy".
C.4 Changes from draft-ietf-xmpp-core-01 C.5 Changes from draft-ietf-xmpp-core-01
o Updated the addressing restrictions per list discussion and added o Updated the addressing restrictions per list discussion and added
references to the new nodeprep and resourceprep profiles. references to the new nodeprep and resourceprep profiles.
o Corrected error in Stream Authentication regarding "version='1.0'" o Corrected error in Stream Authentication regarding "version='1.0'"
flag. flag.
o Made numerous small editorial changes. o Made numerous small editorial changes.
C.5 Changes from draft-ietf-xmpp-core-00 C.6 Changes from draft-ietf-xmpp-core-00
o Added information about TLS from list discussion. o Added information about TLS from list discussion.
o Clarified meaning of "ignore" based on list discussion. o Clarified meaning of "ignore" based on list discussion.
o Clarified information about Universal Character Set data and o Clarified information about Universal Character Set data and
character encodings. character encodings.
o Provided base64-decoded information for examples. o Provided base64-decoded information for examples.
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
o Made numerous small editorial fixes. o Made numerous small editorial fixes.
C.6 Changes from draft-miller-xmpp-core-02 C.7 Changes from draft-miller-xmpp-core-02
o Brought Streams Authentication section into line with discussion o Brought Streams Authentication section into line with discussion
on list and at IETF 55 meeting. on list and at IETF 55 meeting.
o Added information about the optional 'xml:lang' attribute per o Added information about the optional 'xml:lang' attribute per
discussion on list and at IETF 55 meeting. discussion on list and at IETF 55 meeting.
o Specified that validation is neither required nor recommended, and o Specified that validation is neither required nor recommended, and
that the formal definitions (DTDs and schemas) are included for that the formal definitions (DTDs and schemas) are included for
descriptive purposes only. descriptive purposes only.
skipping to change at page 72, line 5 skipping to change at page 72, line 5
o Noted that XMPP activity respects firewall administration o Noted that XMPP activity respects firewall administration
policies. policies.
o Further specified the scope and uniqueness of the 'id' attribute o Further specified the scope and uniqueness of the 'id' attribute
in all stanza types and the <thread/> element in message stanzas. in all stanza types and the <thread/> element in message stanzas.
o Nomenclature changes: (1) from "chunks" to "stanzas"; (2) from o Nomenclature changes: (1) from "chunks" to "stanzas"; (2) from
"host" to "server" and from "node" to "client" (except with regard "host" to "server" and from "node" to "client" (except with regard
to definition of the addressing scheme). to definition of the addressing scheme).
Intellectual Property Statement
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Acknowledgement Acknowledgement
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