draft-ietf-xmpp-core-10.txt   draft-ietf-xmpp-core-11.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft J. Miller Internet-Draft J. Miller
Expires: October 20, 2003 Jabber Software Foundation Expires: October 26, 2003 Jabber Software Foundation
April 21, 2003 April 27, 2003
XMPP Core XMPP Core
draft-ietf-xmpp-core-10 draft-ietf-xmpp-core-11
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 elements and Presence Protocol (XMPP), a protocol for streaming XML elements
in order to exchange messages and presence information in close to in order to exchange messages and presence information in close to
real time. XMPP is used mainly for the purpose of building instant real time. XMPP is used mainly for the purpose of building instant
messaging (IM) and presence applications, such as the servers and messaging (IM) and presence applications, such as the servers and
clients that comprise the Jabber network. clients 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 . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
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 Stream Attributes . . . . . . . . . . . . . . . . . . . . 11 4.2 Stream Attributes . . . . . . . . . . . . . . . . . . . . . 11
4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . 12 4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . . 12
4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . 13 4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . . 13
4.5 Stream Errors . . . . . . . . . . . . . . . . . . . . . . 14 4.5 Stream Errors . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . 15 4.5.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.5.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . 16 4.5.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 16
4.6 Simple Streams Example . . . . . . . . . . . . . . . . . . 16 4.6 Simple Streams Example . . . . . . . . . . . . . . . . . . . 16
5. Stream Encryption . . . . . . . . . . . . . . . . . . . . 19 5. Stream Encryption . . . . . . . . . . . . . . . . . . . . . 19
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . 21 5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . . 21
5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . 23 5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . . 23
6. Stream Authentication . . . . . . . . . . . . . . . . . . 26 6. Stream Authentication . . . . . . . . . . . . . . . . . . . 26
6.1 SASL Authentication . . . . . . . . . . . . . . . . . . . 26 6.1 SASL Authentication . . . . . . . . . . . . . . . . . . . . 26
6.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 26 6.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 27 6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . 29 6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 29
6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . 30 6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . . 30
6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . 32 6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . . 32
6.2 Dialback Authentication . . . . . . . . . . . . . . . . . 35 6.2 Dialback Authentication . . . . . . . . . . . . . . . . . . 35
6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . 37 6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . . 37
7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . 42 7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 42
7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . 42 7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . . 42
7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . 44 7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . . 44
7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . 44 7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . . 44
7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.3.2.1 Body . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . . 46
7.3.2.2 Subject . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . . 46
7.3.2.3 Thread . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 47
7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . 46 7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . 46 7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . 46 7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . . 49
7.4.2.1 Show . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.4.2.2 Status . . . . . . . . . . . . . . . . . . . . . . . . . . 47 7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . . 50
7.4.2.3 Priority . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 51
7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 48 7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . 49 7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 52
7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 53
7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . 49 8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 54
7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . 50 8.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 54
7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 50 8.2 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 51 8.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . 52 8.4 Character Encodings . . . . . . . . . . . . . . . . . . . . 55
7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . 53 8.5 Inclusion of Text Declaration . . . . . . . . . . . . . . . 55
8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . 54 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 56
8.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . 54 9.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . . 56
8.2 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . 54 9.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . . 56
8.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . 54 9.3 XML Namespace Name for Stream Errors . . . . . . . . . . . . 56
8.4 Character Encodings . . . . . . . . . . . . . . . . . . . 55 9.4 XML Namespace Name for Stanza Errors . . . . . . . . . . . . 57
8.5 Inclusion of Text Declaration . . . . . . . . . . . . . . 55 9.5 Existing Registrations . . . . . . . . . . . . . . . . . . . 57
9. IANA Considerations . . . . . . . . . . . . . . . . . . . 56 10. Internationalization Considerations . . . . . . . . . . . . 58
9.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . 56 11. Security Considerations . . . . . . . . . . . . . . . . . . 59
9.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . 56 11.1 High Security . . . . . . . . . . . . . . . . . . . . . . . 59
9.3 XML Namespace Name for Stream Errors . . . . . . . . . . . 56 11.2 Client-to-Server Communications . . . . . . . . . . . . . . 59
9.4 XML Namespace Name for Stanza Errors . . . . . . . . . . . 57 11.3 Server-to-Server Communications . . . . . . . . . . . . . . 60
9.5 Existing Registrations . . . . . . . . . . . . . . . . . . 57 11.4 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . 60
10. Internationalization Considerations . . . . . . . . . . . 58 11.5 Mandatory to Implement Technologies . . . . . . . . . . . . 60
11. Security Considerations . . . . . . . . . . . . . . . . . 59 Normative References . . . . . . . . . . . . . . . . . . . . 61
11.1 High Security . . . . . . . . . . . . . . . . . . . . . . 59 Informative References . . . . . . . . . . . . . . . . . . . 63
11.2 Client-to-Server Communications . . . . . . . . . . . . . 59 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 63
11.3 Server-to-Server Communications . . . . . . . . . . . . . 60 A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 65
11.4 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . 60 A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . . 65
11.5 Mandatory to Implement Technologies . . . . . . . . . . . 60 A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 66
Normative References . . . . . . . . . . . . . . . . . . . 61 A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 66
Informative References . . . . . . . . . . . . . . . . . . 63 A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 67
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 63 A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . . 68
A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . 65 A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . . 72
A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . 65 A.7 Stream error namespace . . . . . . . . . . . . . . . . . . . 75
A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . 66 A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . . 76
A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . 66 B. Revision History . . . . . . . . . . . . . . . . . . . . . . 78
A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . 67 B.1 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . . 78
A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . 68 B.2 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . . 78
A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . 72 B.3 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . . 78
A.7 Stream error namespace . . . . . . . . . . . . . . . . . . 75 B.4 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . . 78
A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . 76 B.5 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . . 79
B. Revision History . . . . . . . . . . . . . . . . . . . . . 78 B.6 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 79
B.1 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . 78 B.7 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 79
B.2 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . 78 B.8 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 79
B.3 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . 78 B.9 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 80
B.4 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . 78 B.10 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 80
B.5 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . 79 B.11 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 80
B.6 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . 79 Intellectual Property and Copyright Statements . . . . . . . 82
B.7 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . 79
B.8 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . 79
B.9 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . 79
B.10 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . 80
B.11 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . 80
Full Copyright Statement . . . . . . . . . . . . . . . . . 82
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 request- [1] protocol for near-real-time messaging, presence, and
response services. The basic syntax and semantics were developed request-response services. The basic syntax and semantics were
originally within the Jabber open-source community, mainly in 1999. developed originally within the Jabber open-source community, mainly
In 2002, the XMPP WG was chartered with developing an adaptation of in 1999. In 2002, the XMPP WG was chartered with developing an
the Jabber protocol that would be suitable as an IETF instant adaptation of the Jabber protocol that would be suitable as an IETF
messaging and presence technology. As a result of work by the XMPP instant messaging and presence technology. As a result of work by the
WG, the current document defines the core features of XMPP; XMPP IM XMPP WG, the current document defines the core features of XMPP; XMPP
[22] defines the extensions required to provide the instant messaging IM [23] defines the extensions required to provide the instant
(IM) and presence functionality defined in RFC 2779 [2]. messaging (IM) and presence functionality defined in RFC 2779 [2].
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 [3]. 2119 [3].
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 client- this point it has usually been implemented via a typical
server architecture, wherein a client utilizing XMPP accesses a client-server architecture, wherein a client utilizing XMPP accesses
server over a TCP [4] socket. a server over a TCP [4] 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 25 skipping to change at page 7, line 22
socket and differentiated by the resource identifier of a JID socket and differentiated by the resource identifier of a JID
(Section 3) (e.g., user@domain/home vs. user@domain/work). The port (Section 3) (e.g., user@domain/home vs. user@domain/work). The port
registered with the IANA [5] for connections between a Jabber client registered with the IANA [5] for connections between a Jabber client
and a Jabber server is 5222. and a Jabber server is 5222.
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 used by a foreign function is to translate XMPP into the protocol used by a foreign
(non-XMPP) messaging system, as well as to translate the return data (non-XMPP) messaging system, as well as to translate the return data
back into XMPP. Examples are gateways to SIMPLE, Internet Relay Chat back into XMPP. Examples are gateways to Internet Relay Chat (IRC),
(IRC), Short Message Service (SMS), SMTP, and legacy instant Short Message Service (SMS), SMTP, and legacy instant messaging
messaging networks such as AIM, ICQ, MSN Messenger, and Yahoo! networks such as AIM, ICQ, MSN Messenger, and Yahoo! Instant
Instant Messenger. Communications between gateways and servers, and Messenger. Communications between gateways and servers, and between
between gateways and the foreign messaging system, are not defined in gateways and the foreign messaging system, are not defined in this
this document. 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 inter- practice the system consists of a network of servers that
communicate. Thus user-a@domain1 is able to exchange messages, inter-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 IANA- network addressing standards. There are two methods for negotiating a
registered port 5269, there are two methods for negotiating a
connection between any two servers: primarily SASL authentication connection between any two servers: primarily SASL authentication
(Section 6.1) and secondarily server dialback (Section 6.2). (Section 6.1) and secondarily server dialback (Section 6.2).
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. (i.e., an ID on the network) and that can communicate using XMPP. All
All such entities are uniquely addressable in a form that is such entities are uniquely addressable in a form that is consistent
consistent with RFC 2396 [23]. In particular, a valid Jabber with RFC 2396 [24]. In particular, a valid Jabber Identifier (JID)
Identifier (JID) contains a set of ordered elements formed of a contains a set of ordered elements formed of a domain identifier,
domain identifier, node identifier, and resource identifier in the node identifier, and resource identifier in the following format:
following format: [node@]domain[/resource]. [node@]domain[/resource].
All JIDs are based on the foregoing structure. The most common use All JIDs are based on the foregoing structure. The most common use of
of this structure is to identify an IM user, the server to which the 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 [6] and RFC 1123 Name. A domain identifier MUST conform to RFC 952 [6] and RFC 1123
[7]. A domain identifier MUST be no more than 1023 bytes in length [7]. A domain identifier MUST be no more than 1023 bytes in length
and MUST conform to the nameprep [8] profile of stringprep [9]. and MUST conform to the nameprep [8] profile of stringprep [9].
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 associated with a multi-user chat service). The entity represented by
by a node identifier is addressed within the context of a specific 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 [10] profile of stringprep [9]. conform to the nodeprep [10] profile of stringprep [9].
3.4 Resource Identifier 3.4 Resource Identifier
The resource identifier is an optional tertiary identifier, which may The resource identifier is an optional tertiary identifier, which may
modify either a "user@domain" or mere "domain" address. It usually modify either a "user@domain" or mere "domain" address. It usually
represents a specific session, connection (e.g., a device or 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. A belonging to the entity associated with a node identifier. A resource
resource identifier is typically defined by a client implementation identifier is typically defined by a client implementation and is
and is opaque to both servers and other clients. An entity may opaque to both servers and other clients. An entity may maintain
maintain multiple resources simultaneously. 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 [11] profile of stringprep [9]. MUST conform to the resourceprep [11] profile of stringprep [9].
4. XML Streams 4. XML Streams
4.1 Overview 4.1 Overview
Two fundamental concepts make possible the rapid, asynchronous Two fundamental concepts make possible the rapid, asynchronous
exchange of relatively small payloads of structured information exchange of relatively small payloads of structured information
between presence-aware entities: XML streams and XML stanzas. The between presence-aware entities: XML streams and XML stanzas. The
terms may be defined as follows: terms may be defined as follows:
Definition of XML stream: An XML stream is a container for the Definition of XML stream: An XML stream is a container for the
exchange of XML elements between any two entities over a network. exchange of XML elements between any two entities over a network.
An XML stream is negotiated from an initiating entity (usually a An XML stream is negotiated from an initiating entity (usually a
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, and corresponds to the initiating normally over a TCP socket, and corresponds to the initiating
entity's "session" with the receiving entity. The start of the entity's "session" with the receiving entity. The start of the XML
XML stream is denoted unambiguously by an opening XML <stream> tag stream is denoted unambiguously by an opening XML <stream> tag
with appropriate attributes and namespace declarations, and the with appropriate attributes and namespace declarations, and the
end of the XML stream is denoted unambiguously be a closing XML </ end of the XML stream is denoted unambiguously be a closing XML </
stream> tag. An XML stream is unidirectional; in order to enable stream> tag. An XML stream is unidirectional; in order to enable
bidirectional information exchange, the initiating entity and bidirectional information exchange, the initiating entity and
receiving entity must negotiate one stream in each direction, receiving entity must negotiate one stream in each direction,
normally over the same TCP connection. normally over the same TCP connection.
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 over an XML stream. An XML stanza exists at the direct child level
level of the root <stream/> element and is said to be well- of the root <stream/> element and is said to be well-balanced if
balanced if it matches production [43] content of the XML it matches production [43] content of the XML specification [1]).
specification [1]). The start of any XML stanza is denoted The start of any XML stanza is denoted unambiguously by the
unambiguously by the element start tag at depth=1 (e.g., element start tag at depth=1 (e.g., <presence>), and the end of
<presence>), and the end of any XML stanza is denoted any XML stanza is denoted unambiguously by the corresponding close
unambiguously by the corresponding close tag at depth=1 (e.g., </ tag at depth=1 (e.g., </presence>). An XML stanza MAY contain
presence>). An XML stanza MAY contain child elements (with child elements (with accompanying attributes, elements, and CDATA)
accompanying attributes, elements, and CDATA) as necessary in as necessary in order to convey the desired information.
order to convey the desired information.
Consider the example of a client's session with a server. In order Consider the example of a client's session with a server. In order to
to connect to a server, a client must initiate an XML stream by connect to a server, a client must initiate an XML stream by sending
sending an opening <stream> tag to the server, optionally preceded by an opening <stream> tag to the server, optionally preceded by a text
a text declaration specifying the XML version supported and the declaration specifying the XML version supported and the character
character encoding. The server SHOULD then reply with a second XML encoding. The server SHOULD then reply with a second XML stream back
stream back to the client, again optionally preceded by a text to the client, again optionally preceded by a text declaration. Once
declaration. Once the client has authenticated with the server (see the client has authenticated with the server (see Section 6), the
Section 6), the client MAY send an unlimited number of XML stanzas client MAY send an unlimited number of XML stanzas over the stream to
over the stream to any recipient on the network. When the client any recipient on the network. When the client desires to close the
desires to close the stream, it simply sends a closing </stream> tag stream, it simply sends a closing </stream> tag to the server
to the server (alternatively, the session may be closed by the (alternatively, the session may be closed by the server), after which
server), after which both the client and server SHOULD close the both the client and server SHOULD close the underlying TCP connection
underlying TCP connection as well. as well.
Those who are accustomed to thinking of XML in a document-centric Those who are accustomed to thinking of XML in a document-centric
manner may wish to view a client's session with a server as manner may wish to view a client's session with a server as
consisting of two open-ended XML documents: one from the client to consisting of two open-ended XML documents: one from the client to
the server and one from the server to the client. From this the server and one from the server to the client. From this
perspective, the root <stream/> element can be considered the perspective, the root <stream/> element can be considered the
document entity for each "document", and the two "documents" are document entity for each "document", and the two "documents" are
built up through the accumulation of XML stanzas sent over the two built up through the accumulation of XML stanzas sent over the two
XML streams. However, this perspective is a convenience only, and XML streams. However, this perspective is a convenience only, and
XMPP does not deal in documents but in XML streams and XML stanzas. XMPP does not deal in documents but in XML streams and XML stanzas.
skipping to change at page 13, line 31 skipping to change at page 13, line 30
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 jabber:server. If a compliant implementation accepts a stream that is
is scoped by the 'jabber:client' or 'jabber:server' namespace, it scoped by the 'jabber:client' or 'jabber:server' namespace, it MUST
MUST support all three core stanza types (message, presence, and IQ) support all three core stanza types (message, presence, and IQ) as
as described herein and defined in the schema. described herein and defined in the schema.
4.4 Stream Features 4.4 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, stream. Currently this is used for SASL and TLS negotiation only, but
but it could be used for other negotiable features in the future it could be used for other negotiable features in the future (usage
(usage is defined under Stream Encryption (Section 5) and Stream 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 silently ignore them. or support some features, it SHOULD silently ignore them.
4.5 Stream Errors 4.5 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 compliant entity (usually a server error child MUST be sent by a compliant entity (usually a server
rather than a client) if it perceives that a stream-level error has rather than a client) if it perceives that a stream-level error has
occurred. occurred.
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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 <condition/> element MUST contain a child element that specifies The <condition/> element MUST contain a child element that specifies
a particular stream-level error condition, as defined in the next a particular stream-level error condition, as defined in the next
section. (Note: the XML namespace name 'urn:ietf:params:xml:ns:xmpp- section. (Note: the XML namespace name
streams' that scopes the <condition/> element adheres to the format 'urn:ietf:params:xml:ns:xmpp-streams' that scopes the <condition/>
defined in The IETF XML Registry [24].) element adheres to the format defined in The IETF XML Registry [25].)
4.5.3 Conditions 4.5.3 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".
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</stream:error> </stream:error>
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) [13] protocol, along with a "STARTTLS" Transport Layer Security (TLS) [13] protocol, along with a "STARTTLS"
extension that is modelled on similar extensions for the IMAP [25], extension that is modelled on similar extensions for the IMAP [26],
POP3 [26], and ACAP [27] protocols as described in RFC 2595 [28]. POP3 [27], and ACAP [28] protocols as described in RFC 2595 [29]. The
The namespace identifier for the STARTTLS extension is namespace identifier for the STARTTLS extension is
'urn:ietf:params:xml:ns:xmpp-tls'. 'urn:ietf:params:xml:ns:xmpp-tls'.
TLS SHOULD be used between any initiating entity and any receiving TLS SHOULD be used between any initiating entity and any receiving
entity (e.g., a stream from a client to a server or from one server entity (e.g., a stream from a client to a server or from one server
to another). An administrator of a given domain MAY require use of to another). An administrator of a given domain MAY require use of
TLS for either or both client-to-server communications and server-to- TLS for either or both client-to-server communications and
server communications. Servers SHOULD use TLS betweeen two domains server-to-server communications. Servers SHOULD use TLS betweeen two
for the purpose of securing server-to-server communcations. When the domains for the purpose of securing server-to-server communcations.
remote domain is already known, the server can verify the credentials When the remote domain is already known, the server can verify the
of the known domain by comparing known keys or certificates. When credentials of the known domain by comparing known keys or
the remote domain is not recognized, it may still be possible to certificates. When the remote domain is not recognized, it may still
verify a certificate if it is signed by a common trusted authority. be possible to verify a certificate if it is signed by a common
Even if there is no way to verify certificates (e.g., an unknown trusted authority. Even if there is no way to verify certificates
domain with a self-signed certificate, or a certificate signed by an (e.g., an unknown domain with a self-signed certificate, or a
unrecognized authority), if the servers choose to communicate despite certificate signed by an unrecognized authority), if the servers
the lack of verified credentials, TLS still SHOULD be used to provide choose to communicate despite the lack of verified credentials, TLS
encryption. still SHOULD be used to provide encryption.
The following business rules apply: The following business rules apply:
1. An initiating entity that complies with this specification MUST 1. An initiating entity that complies with this specification MUST
include the "version='1.0'" flag in the initiating stream header. include the "version='1.0'" flag in the initiating stream header.
2. When a receiving entity that complies with this specification 2. When a receiving entity that complies with this specification
receives an initiating stream header that includes the receives an initiating stream header that includes the
"version='1.0'" flag, after sending a stream header in reply it "version='1.0'" flag, after sending a stream header in reply it
MUST also send a <starttls/> element scoped by the MUST also send a <starttls/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace as well as the list 'urn:ietf:params:xml:ns:xmpp-tls' namespace as well as the list
of other stream features it supports. of other stream features it supports.
3. If the initiating entity chooses to use TLS for stream 3. If the initiating entity chooses to use TLS for stream
encryption, TLS negotiation MUST be completed before proceeding encryption, TLS negotiation MUST be completed before proceeding
to SASL negotiation. to SASL negotiation.
4. The initiating entity MUST validate the certificate presented by 4. The initiating entity MUST validate the certificate presented by
the receiving entity: the receiving entity:
1. If the initiating entity has been configured with a set of Case 1 -- The initiating entity has been configured with a set of
trusted roots, either a well-known public set or a manually trusted root certificates: Normal certificate validation
configured Certificate Authority (e.g., an organization's own processing is appropriate, and SHOULD follow the rules defined
Certificate Authority), normal certificate validation for HTTP over TLS [14]. The trusted roots may be either a
processing is appropriate. well-known public set or a manually configured Root CA (e.g.,
an organization's own Certificate Authority or a self-signed
Root CA for the service as described under High Security
(Section 11.1)). This case is RECOMMENDED.
2. If the initiating entity has been configured with the Case 2 -- The initiating entity has been configured with the
receiving entity's public key or certificate, a simple receiving entity's self-signed service certificate: Simple
comparison is appropriate. comparison of public keys is appropriate. This case is NOT
RECOMMENDED (see High Security (Section 11.1) for details).
If the above methods fail, the certificate MAY be presented to a If the above methods fail, the certificate SHOULD be presented to
user for approval; the user SHOULD be given the option to store a user for approval; if presented, the receiver MUST deliver the
the certificate and not ask again for at least some reasonable entire certificate chain to the user, who SHOULD be given the
period of time. option to store the Root CA certificate (not the service or End
Entity certificate) and to not be queried again regarding
acceptance of the certificate for some reasonable period of time.
5. If the TLS negotiation is successful, the receiving entity MUST 5. If the TLS negotiation is successful, the receiving entity MUST
discard any knowledge obtained from the initiating entity before discard any knowledge obtained from the initiating entity before
TLS takes effect. TLS takes effect.
6. If the TLS negotiation is successful, the initiating entity MUST 6. If the TLS negotiation is successful, the initiating entity MUST
discard any knowledge obtained from the receiving entity before discard any knowledge obtained from the receiving entity before
TLS takes effect. TLS takes effect.
7. If the TLS negotiation is successful, the receiving entity MUST 7. If the TLS negotiation is successful, the receiving entity MUST
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4. The initiating entity issues the STARTTLS command to instruct the 4. The initiating entity issues the STARTTLS command to instruct the
receiving entity that it wishes to begin a TLS negotiation to receiving entity that it wishes to begin a TLS negotiation to
secure the stream. secure the stream.
5. The receiving entity MUST reply with either a <proceed/> element 5. The receiving entity MUST reply with either a <proceed/> element
or a <failure/> element scoped by the or a <failure/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace, but keep the 'urn:ietf:params:xml:ns:xmpp-tls' namespace, but keep the
underlying TCP connection open. underlying TCP connection open.
6. The initiating entity begins a TLS negotiation in accordance with 6. The initiating entity begins a TLS negotiation in accordance with
RFC 2246 [13]. Upon completion of the negotiation, the RFC 2246 [13]. Upon completion of the negotiation, the initiating
initiating entity initiates a new stream by sending a new opening entity initiates a new stream by sending a new opening XML stream
XML stream header to the receiving entity. header to the receiving entity.
7. The receiving entity responds by sending an XML stream header to 7. The receiving entity responds by sending an XML stream header to
the initiating entity along with the remaining available features the initiating entity along with the remaining available features
(but NOT including the STARTTLS element). (but NOT including the STARTTLS element).
5.3 Client-to-Server Example 5.3 Client-to-Server Example
The following example shows the data flow for a client securing a The following example shows the data flow for a client securing a
stream using STARTTLS. stream using STARTTLS (the IANA registers port 5222 for
client-to-server communications using XMPP/Jabber, but another port
MAY be used).
Step 1: Client initiates stream to server: Step 1: Client initiates stream to server:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
to='capulet.com' to='capulet.com'
version='1.0'> version='1.0'>
Step 2: Server responds by sending a stream tag to the client: Step 2: Server responds by sending a stream tag to the client:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
version='1.0'> version='1.0'>
Step 3: Server sends the STARTTLS extension to the client along with Step 3: Server sends the STARTTLS extension to the client along with
authentication mechanisms and any other stream features (if TLS is authentication mechanisms and any other stream features (if TLS is
required for interaction with this server, the server SHOULD signal required for interaction with this server, the server SHOULD signal
that fact by including a <required/> element as a child of the that fact by including a <required/> element as a child of the
<starttls/> element): <starttls/> element):
<stream:features> <stream:features>
<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'>
<required/> <required/>
</starttls> </starttls>
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<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
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 (the IANA registers port 5269 for
server-to-server communications using XMPP/Jabber, but another port
MAY be used).
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'
version='1.0'> version='1.0'>
Step 2: Server2 responds by sending a stream tag to Server1: Step 2: Server2 responds by sending a stream tag to Server1:
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</stream:features> </stream:features>
Step 9: Server1 SHOULD continue with stream authentication (Section Step 9: Server1 SHOULD continue with stream authentication (Section
6). 6).
6. Stream Authentication 6. Stream Authentication
XMPP includes two methods for enforcing authentication at the level XMPP includes two methods for enforcing authentication at the level
of XML streams. The secure and preferred method for authenticating of XML streams. The secure and preferred method for authenticating
streams between two entities uses an XMPP adaptation of the Simple streams between two entities uses an XMPP adaptation of the Simple
Authentication and Security Layer (SASL) [14]. If SASL negotiation Authentication and Security Layer (SASL) [15]. If SASL negotiation is
is not possible, some level of trust MAY be established based on not possible, 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 method is defined between a client and a server). If SASL is used for
for server-to-server authentication, the servers MUST NOT use server-to-server authentication, the servers MUST NOT use dialback.
dialback. For further information about the relative merits of these For further information about the relative merits of these two
two methods, consult Security Considerations (Section 11). methods, consult Security Considerations (Section 11).
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 connection- generalized method for adding authentication support to
based protocols. XMPP uses a generic XML namespace profile for SASL connection-based protocols. XMPP uses a generic XML namespace profile
that conforms to section 4 ("Profiling Requirements") of RFC 2222 for SASL that conforms to section 4 ("Profiling Requirements") of RFC
[14] (the XMPP-specific namespace identifier is 2222 [15] (the XMPP-specific namespace identifier is
'urn:ietf:params:xml:ns:xmpp-sasl'). 'urn:ietf:params:xml:ns:xmpp-sasl').
The following business rules apply: The following business rules apply:
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 NOT be negotiated using SASL). Conversely, if a security layer is
is to be negotiated via SASL, TLS MUST NOT be used. 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 scoped by the within a <mechanisms/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace in response to the 'urn:ietf:params:xml:ns:xmpp-sasl' namespace in response to the
opening stream tag received from the initiating entity. opening stream tag received from the initiating entity.
skipping to change at page 27, line 34 skipping to change at page 27, line 34
charset. charset.
4. The realm-value MUST be no more than 1023 bytes in length and 4. The realm-value MUST be no more than 1023 bytes in length and
MUST conform to the nameprep [8] profile of stringprep [9]. MUST conform to the nameprep [8] profile of stringprep [9].
5. The username-value MUST be no more than 1023 bytes in length and 5. The username-value MUST be no more than 1023 bytes in length and
MUST conform to the nodeprep [10] profile of stringprep [9]. MUST conform to the nodeprep [10] profile of stringprep [9].
6. The response-value MUST be computed in accordance with the 6. The response-value MUST be computed in accordance with the
relevant SASL mechanism as defined by the appropriate RFC (e.g., relevant SASL mechanism as defined by the appropriate RFC (e.g.,
RFC 2831 [15] for digest authentication). RFC 2831 [16] for digest authentication).
7. The resource identifier portion of the authzid-value MUST be no 7. The resource identifier portion of the authzid-value MUST be no
more than 1023 bytes in length and MUST conform to the more than 1023 bytes in length and MUST conform to the
resourceprep [11] profile of stringprep [9]. resourceprep [11] profile of stringprep [9].
6.1.2 Narrative 6.1.2 Narrative
When an initiating entity authenticates with a receiving entity, the When an initiating entity authenticates with a receiving entity, the
steps involved are as follows: steps involved are as follows:
skipping to change at page 28, line 11 skipping to change at page 28, line 11
2. After sending an XML stream header in response, the receiving 2. After sending an XML stream header in response, the receiving
entity sends a list of available SASL authentication mechanisms, entity sends a list of available SASL authentication mechanisms,
each of which is a <mechanism/> element included as a child each of which is a <mechanism/> element included as a child
within a <mechanisms/> container element scoped by the within a <mechanisms/> container element scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace that is sent as a 'urn:ietf:params:xml:ns:xmpp-sasl' namespace that is sent as a
child of a <features/> element in the streams namespace. If child of a <features/> element in the streams namespace. If
channel encryption must be established before a particular channel encryption must be established before a particular
authentication mechanism may be used, the receiving entity MUST authentication mechanism may be used, the receiving entity MUST
NOT provide that mechanism in the list of available SASL NOT provide that mechanism in the list of available SASL
authentication methods. If the initiating entity presents a authentication methods. If the initiating entity presents a valid
valid initiating entity certificate during TLS negotiation, the initiating entity certificate during TLS negotiation, the
receiving entity MAY offer the SASL EXTERNAL mechanism to the receiving entity MAY offer the SASL EXTERNAL mechanism to the
initiating entity during stream authentication (see RFC 2222 initiating entity during stream authentication (see RFC 2222
[14]). [15]).
3. The initiating entity selects a mechanism by sending an <auth/> 3. The initiating entity selects a mechanism by sending an <auth/>
element scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl' element scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl'
namespace to the receiving entity; this element MAY optionally namespace to the receiving entity; this element MAY optionally
contain character data (in SASL terminology the "initial contain character data (in SASL terminology the "initial
response") if the mechanism supports or requires it. If the response") if the mechanism supports or requires it. If the
initiating entity selects the EXTERNAL mechanism for initiating entity selects the EXTERNAL mechanism for
authentication, the authentication credentials shall be taken authentication, the authentication credentials shall be taken
from the certificate presented during TLS negotiation. from the certificate presented during TLS negotiation.
4. If necessary, the receiving entity challenges the initiating 4. If necessary, the receiving entity challenges the initiating
entity by sending a <challenge/> element scoped by the entity by sending a <challenge/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (which entity; this element MAY optionally contain character data (which
MUST be computed in accordance with the SASL mechanism chosen by MUST be computed in accordance with the SASL mechanism chosen by
the initiating entity). the initiating entity).
5. The initiating entity responds to the challenge by sending a 5. The initiating entity responds to the challenge by sending a
<response/> element scoped by the 'urn:ietf:params:xml:ns:xmpp- <response/> element scoped by the
sasl' namespace to the receiving entity; this element MAY 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the receiving
optionally contain character data (which MUST be computed in entity; this element MAY optionally contain character data (which
accordance with the SASL mechanism chosen by the initiating MUST be computed in accordance with the SASL mechanism chosen by
entity). the initiating entity).
6. If necessary, the receiving entity sends more challenges and the 6. If necessary, the receiving entity sends more challenges and the
initiating entity sends more responses. initiating entity sends more responses.
This series of challenge/response pairs continues until one of three This series of challenge/response pairs continues until one of three
things happens: things happens:
1. The initiating entity aborts the handshake by sending an <abort/> 1. The initiating entity aborts the handshake by sending an <abort/>
element to the receiving entity. element to the receiving entity.
2. The receiving entity reports failure of the handshake by sending 2. The receiving entity reports failure of the handshake by sending
a <failure/> element scoped by the 'urn:ietf:params:xml:ns:xmpp- a <failure/> element scoped by the
sasl' namespace to the initiating entity. The particular cause 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
of failure SHOULD be communicated in an appropriate child element entity. The particular cause of failure SHOULD be communicated in
of the <failure/> element. The following conditions are defined: an appropriate child element of the <failure/> element. The
following conditions are defined:
* <authentication-mechanism-too-weak/> * <authentication-mechanism-too-weak/>
* <invalid-realm/> * <invalid-realm/>
* <not-authorized/> * <not-authorized/>
* <password-transition-required/> * <password-transition-required/>
* <temporary-authentication-failure/> * <temporary-authentication-failure/>
3. The receiving entity reports success of the handshake by sending 3. The receiving entity reports success of the handshake by sending
a <success/> element scoped by the 'urn:ietf:params:xml:ns:xmpp- a <success/> element scoped by the
sasl' namespace to the initiating entity; this element MAY 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
optionally contain character data (in SASL terminology entity; this element MAY optionally contain character data (in
"additional data with success"). SASL terminology "additional data with success").
Any character data contained within these elements MUST be encoded Any character data contained within these elements MUST be encoded
using base64. using base64.
6.1.3 SASL Definition 6.1.3 SASL Definition
Section 4 of the SASL specification [14] requires that the following Section 4 of the SASL specification [15] requires that the following
information be supplied by a protocol definition: information be supplied by a protocol definition:
service name: "xmpp" service name: "xmpp"
initiation sequence: After the initiating entity provides an opening initiation sequence: After the initiating entity provides an opening
XML stream header and the receiving entity replies in kind, the XML stream header and the receiving entity replies in kind, the
receiving entity provides a list of acceptable authentication receiving entity provides a list of acceptable authentication
methods. The initiating entity chooses one method from the list methods. The initiating entity chooses one method from the list
and sends it to the receiving entity as the value of the and sends it to the receiving entity as the value of the
'mechanism' attribute possessed by an <auth/> element, optionally 'mechanism' attribute possessed by an <auth/> element, optionally
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including an initial response to avoid a round trip. including an initial response to avoid a round trip.
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. (All of these elements are scoped by the <abort/> element. (All of these elements are scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace.) 'urn:ietf:params:xml:ns:xmpp-sasl' namespace.)
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 headers are sent by both entities. The security layer takes effect
effect immediately following the ">" character of the <response/> immediately following the ">" character of the <response/> element
element for the client and immediately following the closing ">" for the client and immediately following the closing ">" character
character of the <succeed/> element for the server. (Both of of the <succeed/> element for the server. (Both of these elements
these elements are scoped by the 'urn:ietf:params:xml:ns:xmpp- are scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl' namespace.)
sasl' namespace.)
use of the authorization identity: The authorization identity is used use of the authorization identity: The authorization identity is used
by xmpp only in negotiation between a client and a server, and by xmpp only in negotiation between a client and a server, and
denotes the "full JID" (user@domain/resource) requested by the denotes the "full JID" (user@domain/resource) requested by the
user or application associated with the client. user or application associated with the client.
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 (the IANA registers port 5222 for
client-to-server communications using XMPP/Jabber, but another port
MAY be used).
Step 1: Client initiates stream to server: Step 1: Client initiates stream to server:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
to='domain' to='domain'
version='1.0'> version='1.0'>
Step 2: Server responds with a stream tag sent to the client: Step 2: Server responds with a stream tag sent to the client:
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<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
from='domain' from='domain'
version='1.0'> version='1.0'>
6.1.5 Server-to-Server Example 6.1.5 Server-to-Server Example
The following example shows the data flow for a server authenticating The following example shows the data flow for a server authenticating
with another server using SASL. with another server using SASL (the IANA registers port 5269 for
server-to-server communications using XMPP/Jabber, but another port
MAY be used).
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'
version='1.0'> version='1.0'>
Step 2: Server2 responds with a stream tag sent to Server1: Step 2: Server2 responds with a stream tag sent to Server1:
<stream:stream <stream:stream
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between two servers can be trusted as much as the DNS can be trusted. between two servers can be trusted as much as the DNS can be trusted.
The method is called dialback and is used only within XML streams The method is called dialback and is used only within XML streams
that are declared under the "jabber:server" namespace. 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 decidedly not intended as a mechanism for securing or Dialback is decidedly not intended as a mechanism for securing or
encrypting the streams between servers as is done via SASL and TLS, encrypting the streams between servers as is done via SASL and TLS,
only for helping to prevent the spoofing of a server and the sending only for helping to prevent the spoofing of a server and the sending
of false data from it. In particular, dialback authentication is of false data from it. In particular, dialback authentication is
susceptible to DNS poisoning attacks unless DNSSec [29] is used. susceptible to DNS poisoning attacks unless DNSSec [30] is used.
Furthermore, even if the DNS information is accurate, dialback Furthermore, even if the DNS information is accurate, dialback
authentication cannot protect from attacks where the attacker is authentication cannot protect from attacks where the attacker is
capable of hijacking the IP address of the remote domain. Domains capable of hijacking the IP address of the remote domain. Domains
requiring more robust security SHOULD use TLS and SASL as defined requiring more robust security SHOULD use TLS and SASL as defined
above. 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 hostname. All DNS hostname authorized to represent a given hostname. All DNS hostname
resolutions MUST first resolve the hostname using an SRV [17] record resolutions MUST first resolve the hostname using an SRV [18] record
of _jabber._tcp.server. If the SRV lookup fails, the fallback is a of _jabber._tcp.server. If the SRV lookup fails, the fallback is a
normal A lookup to determine the IP address, using the jabber-server normal A lookup to determine the IP address, using the jabber-server
port of 5269 assigned by the Internet Assigned Numbers Authority [5]. port of 5269 assigned by the Internet Assigned Numbers Authority [5].
The method for generating and verifying the keys used in the dialback The method for generating and verifying the keys used in the dialback
protocol MUST take into account the hostnames being used, the random protocol MUST take into account the hostnames being used, the random
ID generated for the stream, and a secret known by the authoritative ID generated for the stream, and a secret known by the authoritative
server's network. Generating unique but verifiable keys is important server's network. Generating unique but verifiable keys is important
to prevent common man-in-the-middle attacks and server spoofing. to prevent common man-in-the-middle attacks and server spoofing.
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2. Originating Server sends a stream header to Receiving Server: 2. Originating Server sends a stream header to Receiving Server:
<stream:stream <stream:stream
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
xmlns='jabber:server' xmlns='jabber:server'
xmlns:db='jabber:server:dialback'> xmlns:db='jabber:server:dialback'>
Note: the 'to' and 'from' attributes are NOT REQUIRED on the Note: the 'to' and 'from' attributes are NOT REQUIRED on the
root stream element. The inclusion of the xmlns:db namespace root stream element. The inclusion of the xmlns:db namespace
declaration with the name shown indicates to Receiving Server declaration with the name shown indicates to Receiving Server
that Originating Server supports dialback. If the namespace that Originating Server supports dialback. If the namespace name
name is incorrect, then Receiving Server MUST generate an is incorrect, then Receiving Server MUST generate an
<invalid-namespace/> stream error condition and terminate both <invalid-namespace/> stream error condition and terminate both
the XML stream and the underlying TCP connection. the XML stream and the underlying TCP connection.
3. Receiving Server SHOULD send a stream header back to Originating 3. Receiving Server SHOULD send a stream header back to Originating
Server, including a unique ID for this interaction: Server, including a unique ID for this interaction:
<stream:stream <stream:stream
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
xmlns='jabber:server' xmlns='jabber:server'
xmlns:db='jabber:server:dialback' xmlns:db='jabber:server:dialback'
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4. Originating Server sends a dialback key to Receiving Server: 4. Originating Server sends a dialback key to Receiving Server:
<db:result <db:result
to='Receiving Server' to='Receiving Server'
from='Originating Server'> from='Originating Server'>
98AF014EDC0... 98AF014EDC0...
</db:result> </db:result>
Note: this key is not examined by Receiving Server, since Note: this key is not examined by Receiving Server, since
Receiving Server does not keep information about Originating Receiving Server does not keep information about Originating
Server between sessions. The key generated by Originating Server between sessions. The key generated by Originating Server
Server must be based in part on the value of the ID provided by must be based in part on the value of the ID provided by
Receiving Server in the previous step, and in part on a secret Receiving Server in the previous step, and in part on a secret
shared by Originating Server and Authoritative Server. If the shared by Originating Server and Authoritative Server. If the
value of the 'to' address does not match a hostname recognized value of the 'to' address does not match a hostname recognized
by Receiving Server, then Receiving Server MUST generate a by Receiving Server, then Receiving Server MUST generate a
<host-unknown/> stream error condition and terminate both the <host-unknown/> stream error condition and terminate both the
XML stream and the underlying TCP connection. If the value of XML stream and the underlying TCP connection. If the value of
the 'from' address matches a domain with which Receiving Server the 'from' address matches a domain with which Receiving Server
already has an established connection, then Receiving Server already has an established connection, then Receiving Server
SHOULD generate a <not-authorized/> stream error condition and SHOULD generate a <not-authorized/> stream error condition and
terminate both the XML stream and the underlying TCP connection. terminate both the XML stream and the underlying TCP connection.
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Note: if the namespace name is incorrect, then Receiving Server Note: if the namespace name is incorrect, then Receiving Server
MUST generate an <invalid-namespace/> stream error condition and MUST generate an <invalid-namespace/> stream error condition and
terminate both the XML stream and the underlying TCP connection terminate both the XML stream and the underlying TCP connection
between it and Authoritative Server. If the ID does not match between it and Authoritative Server. If the ID does not match
that provided by Receiving Server in Step 3, then Receiving that provided by Receiving Server in Step 3, then Receiving
Server MUST generate an <invalid-id/> stream error condition and Server MUST generate an <invalid-id/> stream error condition and
terminate both the XML stream and the underlying TCP connection terminate both the XML stream and the underlying TCP connection
between it and Authoritative Server. If either of the foregoing between it and Authoritative Server. If either of the foregoing
stream errors occurs between Receiving Server and Authoritative stream errors occurs between Receiving Server and Authoritative
Server, then Receiving Server MUST generate a <remote- Server, then Receiving Server MUST generate a
connection-failed/> stream error condition and terminate both <remote-connection-failed/> stream error condition and terminate
the XML stream and the underlying TCP connection between it and both the XML stream and the underlying TCP connection between it
Originating Server. and Originating Server.
8. Receiving Server sends Authoritative Server a stanza requesting 8. Receiving Server sends Authoritative Server a stanza requesting
that Authoritative Server verify a key: that Authoritative Server verify a key:
<db:verify <db:verify
from='Receiving Server' from='Receiving Server'
to='Originating Server' to='Originating Server'
id='457F9224A0...'> id='457F9224A0...'>
98AF014EDC0... 98AF014EDC0...
</db:verify> </db:verify>
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<db:verify <db:verify
from='Originating Server' from='Originating Server'
to='Receiving Server' to='Receiving Server'
type='invalid' type='invalid'
id='457F9224A0...'/> id='457F9224A0...'/>
Note: if the ID does not match that provided by Receiving Server Note: if the ID does not match that provided by Receiving Server
in Step 3, then Receiving Server MUST generate an <invalid-id/> in Step 3, then Receiving Server MUST generate an <invalid-id/>
stream error condition and terminate both the XML stream and the stream error condition and terminate both the XML stream and the
underlying TCP connection. If the value of the 'to' address underlying TCP connection. If the value of the 'to' address does
does not match a hostname recognized by Receiving Server, then not match a hostname recognized by Receiving Server, then
Receiving Server MUST generate a <host-unknown/> stream error Receiving Server MUST generate a <host-unknown/> stream error
condition and terminate both the XML stream and the underlying condition and terminate both the XML stream and the underlying
TCP connection. If the value of the 'from' address does not TCP connection. If the value of the 'from' address does not
match the hostname represented by Originating Server when match the hostname represented by Originating Server when
opening the TCP connection (or any validated domain), then opening the TCP connection (or any validated domain), then
Receiving Server MUST generate a <nonmatching-hosts/> stream Receiving Server MUST generate a <nonmatching-hosts/> stream
error condition and terminate both the XML stream and the error condition and terminate both the XML stream and the
underlying TCP connection. underlying TCP connection.
10. Receiving Server informs Originating Server of the result: 10. Receiving Server informs Originating Server of the result:
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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 "publish- The <presence/> element can be seen as a basic broadcast or
subscribe" mechanism, whereby multiple entities receive information "publish-subscribe" mechanism, whereby multiple entities receive
(in this case, presence information) about an entity to which they information (in this case, presence information) about an entity to
have subscribed. The <iq/> element can be seen as a "request- which they have subscribed. The <iq/> element can be seen as a
response" mechanism similar to HTTP, whereby two entities can engage "request-response" mechanism similar to HTTP, whereby two entities
in a structured conversation using 'get' or 'set' requests and can engage in a structured conversation using 'get' or 'set' requests
'result' or 'error' responses. and '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
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handling by that server (e.g., presence sent to the server for handling by that server (e.g., presence sent to the server for
broadcasting to other entities) MAY legitimately lack a 'to' broadcasting to other entities) MAY legitimately lack a 'to'
attribute. attribute.
In the 'jabber:server' namespace, a stanza MUST possess a 'to' In the 'jabber:server' namespace, a stanza MUST possess a 'to'
attribute; if a server receives a stanza that does not meet this attribute; if a server receives a stanza that does not meet this
restriction, it MUST generate an <invalid-xml/> stream error restriction, it MUST generate an <invalid-xml/> stream error
condition and terminate both the XML stream and the underlying TCP condition and terminate both the XML stream and the underlying TCP
connection. connection.
If the value of the 'to' attribute is invalid or cannot be contacted,
the entity discovering that fact (usually the sender's or recipient's
server) MUST return an appropriate error to the sender.
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 to the sender. In addition, a server MUST stamp stanzas received from
from a client with the user@domain/resource (full JID) of the a client with the user@domain/resource (full JID) of the connected
connected resource that generated the stanza. resource that generated the stanza as defined by the authzid provided
in the SASL negotiation.
In the 'jabber:server' namespace, a stanza MUST possess a 'from' In the 'jabber:server' namespace, a stanza MUST possess a 'from'
attribute; if a server receives a stanza that does not meet this attribute; if a server receives a stanza that does not meet this
restriction, it MUST generate an <invalid-xml/> stream error restriction, it MUST generate an <invalid-xml/> stream error
condition. Furthermore, the domain identifier portion of the JID condition. Furthermore, the domain identifier portion of the JID
contained in the 'from' attribute MUST match the hostname of the contained in the 'from' attribute MUST match the hostname of the
sending server (or any validated domain) as communicated in the SASL sending server (or any validated domain) as communicated in the SASL
negotiation or dialback negotiation; if a server receives a stanza negotiation or dialback negotiation; if a server receives a stanza
that does not meet this restriction, it MUST generate a <nonmatching- that does not meet this restriction, it MUST generate a
hosts/> stream error condition. Both of these conditions MUST result <nonmatching-hosts/> stream error condition. Both of these conditions
in closing of the stream and termination of the underlying TCP MUST result in closing of the stream and termination of the
connection. underlying TCP connection.
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
or presence stanza MAY return that 'id' in any replies, but is NOT or presence stanza MAY return that 'id' in any replies, but is NOT
REQUIRED to do so. REQUIRED to do so.
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7.2.4 type 7.2.4 type
The 'type' attribute specifies detailed information about the purpose The 'type' attribute specifies detailed information about the purpose
or context of the message, presence, or IQ stanza. The particular or context of the message, presence, or IQ stanza. The particular
allowable values for the 'type' attribute vary depending on whether allowable values for the 'type' attribute vary depending on whether
the stanza is a message, presence, or IQ, and thus are specified in the stanza is a message, presence, or IQ, and thus are specified in
the following sections. the following sections.
7.2.5 xml:lang 7.2.5 xml:lang
Any message or presence stanza MAY possess an 'xml:lang' attribute Any message or presence stanza MAY possess an 'xml:lang' attribute as
specifying the default language of any CDATA sections of the stanza defined in Section 2.12 of the XML specification [1]. Ths value this
or its child elements. An IQ stanza SHOULD NOT possess an 'xml:lang' attribute specifies the default language of any XML character data
attribute, since it is merely a vessel for data in other namespaces contained in the stanza or its child elements. An IQ stanza SHOULD
and does not itself contain children that have CDATA. The value of NOT possess an 'xml:lang' attribute, since it is merely a vessel for
the 'xml:lang' attribute MUST be an NMTOKEN and MUST conform to the data in other namespaces and does not itself contain children that
format defined in RFC 3066 [16]. have CDATA. The value of the 'xml:lang' attribute MUST be an NMTOKEN
and MUST conform to the format defined in RFC 3066 [17].
7.3 Message Stanzas 7.3 Message Stanzas
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 specifies the conversational context of the message. The sending of a
a message stanza without a 'type' attribute signals that the message 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
For information about the meaning of these message types, refer to For information about the meaning of these message types, refer to
XMPP IM [22]. XMPP IM [23].
7.3.2 Children 7.3.2 Children
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". "http://etherx.jabber.org/streams".
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 stanzas. If the message stanza is of type "error", it MUST include an
an <error/> child; for details, see Section 7.7. If the message <error/> child; for details, see Section 7.7. If the message stanza
stanza has no 'type' attribute or has a 'type' attribute with a value has no 'type' attribute or has a 'type' attribute with a value of
of "chat", "groupchat", or "headline", it MAY contain any of the "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 SHOULD NOT normally included but NOT REQUIRED. The <body/> element SHOULD 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 SHOULD NOT possess any attributes, with the <subject/> element SHOULD 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. possesses an 'xml:lang' attribute with a distinct language value. The
The <subject> element MUST NOT contain mixed content. <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 element MUST be treated as an opaque string by entities; no semantic
semantic meaning may be derived from it, and only exact, case- meaning may be derived from it, and only exact, case-insensitve
insensitve comparisons be made against it. The <thread> element MUST comparisons be made against it. The <thread> element MUST NOT contain
NOT contain mixed content. 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@domain/resource) with the 1. concatenate the sender's full JID (user@domain/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
3. hash the resulting string according to the SHA1 algorithm 3. hash the resulting string according to the SHA1 algorithm
4. convert the hexidecimal SHA1 output to all lowercase 4. convert the hexidecimal SHA1 output to all lowercase
7.4 Presence Stanzas 7.4 Presence Stanzas
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o unsubscribed -- The subscription request has been denied or a o unsubscribed -- The subscription request has been denied or a
previously-granted subscription has been cancelled. previously-granted subscription has been cancelled.
o probe -- A request for an entity's current presence. In general o probe -- A request for an entity's current presence. In general
SHOULD NOT be sent by a client. SHOULD NOT be sent by a client.
o error -- An error has occurred regarding processing or delivery of o error -- An error has occurred regarding processing or delivery of
a previously-sent presence stanza. a previously-sent presence stanza.
Information about the subscription model used within XMPP can be Information about the subscription model used within XMPP can be
found in XMPP IM [22]. found in XMPP IM [23].
7.4.2 Children 7.4.2 Children
As described under extended namespaces (Section 7.6), a presence As described under extended namespaces (Section 7.6), a presence
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". "http://etherx.jabber.org/streams".
In accordance with the default namespace declaration, by default a In accordance with the default namespace declaration, by default a
presence stanza is in the 'jabber:client' or 'jabber:server' presence stanza is in the 'jabber:client' or 'jabber:server'
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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
[22]. [23].
7.4.2.2 Status 7.4.2.2 Status
The optional <status/> element contains a natural-language The optional <status/> element contains 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 SHOULD NOT possess any attributes, with the exception of the element SHOULD NOT possess any attributes, with the exception of the
'xml:lang' attribute. Multiple instances of the <status/> element 'xml:lang' attribute. Multiple instances of the <status/> element MAY
MAY be included but only if each instance possesses an 'xml:lang' 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 connected resource. The value may be any integer between -128 to 127.
127. Only one <priority/> element MAY be included in a presence Only one <priority/> element MAY be included in a presence stanza,
stanza, and it MUST NOT possess any attributes. For information and it MUST NOT possess any attributes. For information regarding the
regarding the use of priority values in stanza routing within IM use of priority values in stanza routing within IM applications, see
applications, see XMPP IM [22]. XMPP IM [23].
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 [30]. IQ stanzas in the 'jabber:client' or ways to HTTP [31]. 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
direct child element of the IQ element, and the interaction is direct child element of the IQ element, and the interaction is
tracked by the requesting entity through use of the 'id' attribute, tracked by the requesting entity through use of the 'id' attribute,
which responding entities SHOULD return in any response. which responding entities SHOULD return in any response.
Most IQ interactions follow a common pattern of structured data Most IQ interactions follow a common pattern of structured data
exchange such as get/result or set/result (although an error may be exchange such as get/result or set/result (although an error may be
returned in response to a request if appropriate): returned in response to a request if appropriate):
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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 (e.g., an encrypted form of the message body). This child element MAY
MAY be have any name and MUST possess an 'xmlns' namespace be have any name and MUST possess an 'xmlns' namespace declaration
declaration (other than "jabber:client", "jabber:server", or "http:// (other than "jabber:client", "jabber:server", or "http://
etherx.jabber.org/streams") that defines all data contained within etherx.jabber.org/streams") that defines all data contained within
the child element. 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, the entity's expected behavior depends on whether the namespace, the entity's expected behavior depends on whether the
entity is (1) the recipient or (2) an entity that is routing the entity is (1) the recipient or (2) an entity that is routing the
stanza to the recipient. In particular: stanza to the recipient. In particular:
Recipient: If a recipient receives a stanza that contains a child Recipient: If a recipient receives a stanza that contains a child
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understand, the entity SHOULD return an IQ stanza of type understand, the entity SHOULD return an IQ stanza of type
"error" with an error condition of <feature-not-implemented/>. "error" with an error condition of <feature-not-implemented/>.
Router: If a routing entity (usually a server) handles a stanza that Router: If a routing entity (usually a server) handles a stanza that
contains a child element it does not understand, it SHOULD ignore contains a child element it does not understand, it SHOULD ignore
the associated XML data by passing it on untouched to the the associated XML data by passing it on untouched to the
recipient. recipient.
7.7 Stanza Errors 7.7 Stanza Errors
As defined below, stanza-related errors are handled in a manner As defined herein, stanza-related errors are handled in a manner
similar to stream errors (Section 4.5). similar to stream errors (Section 4.5).
7.7.1 Rules 7.7.1 Rules
The following rules apply to stanza-related errors: The following rules apply to stanza-related errors:
o A stanza of type "error" MUST contain an <error/> child element. o A stanza of type "error" MUST contain an <error/> child element.
o The receiving or processing entity that returns an error to the o The receiving or processing entity that returns an error to the
sending entity SHOULD include the original XML sent along with the sending entity SHOULD include the original XML sent along with the
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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 'urn:ietf:params:xml:ns:xmpp- specified in a namespace other than
stanzas' 'urn:ietf:params:xml:ns:xmpp-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 <condition/> element MUST contain a child element that specifies The <condition/> element MUST contain a child element that specifies
a particular stanza-related error condition, as defined in the next a particular stanza-related error condition, as defined in the next
section. (Note: the XML namespace name 'urn:ietf:params:xml:ns:xmpp- section. (Note: the XML namespace name
stanzas' that scopes the <condition/> element adheres to the format 'urn:ietf:params:xml:ns:xmpp-stanzas' that scopes the <condition/>
defined in The IETF XML Registry [24].) element adheres to the format defined in The IETF XML Registry [25].)
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".
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o internal or external entity references (Section 4.2) with the o internal or external entity references (Section 4.2) with the
exception of predefined entities (Section 4.6) exception of predefined entities (Section 4.6)
With regard to XML processing, if an XMPP implementation receives With regard to XML processing, if an XMPP implementation receives
such restricted XML data, it MUST ignore the data. such restricted XML data, it MUST ignore the data.
8.2 Namespaces 8.2 Namespaces
XML Namespaces [12] are used within all XMPP-compliant XML to create XML Namespaces [12] are used within all XMPP-compliant XML to create
strict boundaries of data ownership. The basic function of strict boundaries of data ownership. The basic function of namespaces
namespaces is to separate different vocabularies of XML elements that is to separate different vocabularies of XML elements that are
are structurally mixed together. Ensuring that XMPP-compliant XML is 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.
8.3 Validation 8.3 Validation
Except as noted with regard to 'to' and 'from' addresses for stanzas Except as noted with regard to 'to' and 'from' addresses for stanzas
within the 'jabber:server' namespace, a server is not responsible for within the 'jabber:server' namespace, a server is not responsible for
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an implementation MAY choose to provide only validated data elements an implementation MAY choose to provide only validated data elements
but is NOT REQUIRED to do so. Clients SHOULD NOT rely on the ability but is NOT REQUIRED to do so. Clients SHOULD NOT rely on the ability
to send data which does not conform to the schemas, and SHOULD ignore to send data which does not conform to the schemas, and SHOULD ignore
any non-conformant elements or attributes on the incoming XML stream. any non-conformant elements or attributes on the incoming XML stream.
Validation of XML streams and stanzas is NOT REQUIRED or recommended, Validation of XML streams and stanzas is NOT REQUIRED or recommended,
and schemas are included herein for descriptive purposes only. and schemas are included herein for descriptive purposes only.
8.4 Character Encodings 8.4 Character Encodings
Software implementing XML streams MUST support the UTF-8 (RFC 2279 Software implementing XML streams MUST support the UTF-8 (RFC 2279
[18]) and UTF-16 (RFC 2781 [19]) transformations of Universal [19]) and UTF-16 (RFC 2781 [20]) transformations of Universal
Character Set (ISO/IEC 10646-1 [20]) characters. Software MUST NOT Character Set (ISO/IEC 10646-1 [21]) characters. Software MUST NOT
attempt to use any other encoding for transmitted data. The attempt to use any other encoding for transmitted data. The encodings
encodings of the transmitted and received streams are independent. of the transmitted and received streams are independent. Software MAY
Software MAY select either UTF-8 or UTF-16 for the transmitted select either UTF-8 or UTF-16 for the transmitted stream, and SHOULD
stream, and SHOULD deduce the encoding of the received stream as deduce the encoding of the received stream as described in the XML
described in the XML specification [1]. For historical reasons, specification [1]. For historical reasons, existing implementations
existing implementations MAY support UTF-8 only. MAY support UTF-8 only.
8.5 Inclusion of Text Declaration 8.5 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
9.1 XML Namespace Name for TLS Data 9.1 XML Namespace Name for TLS Data
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Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for stanza-related error Description: This is the XML namespace name for stanza-related error
data in the Extensible Messaging and Presence Protocol (XMPP) as data in the Extensible Messaging and Presence Protocol (XMPP) as
defined by [RFCXXXX]. defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org> Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
9.5 Existing Registrations 9.5 Existing Registrations
The IANA registers "xmpp" as a GSSAPI [21] service name, as specified The IANA registers "xmpp" as a GSSAPI [22] service name, as specified
in Section 6.1.3. in Section 6.1.3.
Additionally, the IANA registers "jabber-client" and "jabber-server" Additionally, the IANA registers "jabber-client" and "jabber-server"
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, a server MUST NOT includes an 'xml:lang' attribute in a stanza, a server MUST NOT
modify or delete it. modify or delete it.
11. Security Considerations 11. Security Considerations
11.1 High Security 11.1 High Security
For the purposes of XMPP communications (client-to-server and server- For the purposes of XMPP communications (client-to-server and
to-server), the term "high security" refers to the use of security server-to-server), the term "high security" refers to the use of
technologies that provide both mutual authentication and integrity- security technologies that provide both mutual authentication and
checking; in particular, when using certificate-based authentication integrity-checking; in particular, when using certificate-based
to provide high security, a chain-of-trust SHOULD be established out- authentication to provide high security, a chain-of-trust SHOULD be
of-band, although a shared certificate authority signing certificates established out-of-band, although a shared certificate authority
could allow a previously unknown certificate to establish trust in- signing certificates could allow a previously unknown certificate to
band. establish trust in-band.
Self-signed certificates MAY be used but pose a problem for Standalone, self-signed service certificates SHOULD NOT be used;
administrators the first time such a certificate is seen. A self- rather, an entity that wishes to generate a self-signed service
signed certificate, if accepted, MUST be stored by an entity in order certificate SHOULD first generate a self-signed Root CA certificate
to verify in future communications. A server that changes its self- and then generate a signed service certificate. Entities that
signed cert to another self-signed cert (or to a certificate signed communicate with the service SHOULD be configured with the Root CA
by an unrecognized authority) therefore creates administration certificate rather than the service certificate; this avoids the
problems for all entities with which it has communicated before and problems associated with simple comparison of service certificates.
will again. In particular, those entities have no reason to believe If a self-signed service certificate is used, an entity SHOULD NOT
that the new self-signed cert was not generated by an attacker to trust it if it is changed to another self-signed certificate or a
impersonate the previously-trusted server. certificate signed by an unrecognized authority.
Implementations MUST support high security. Service provisioning Implementations MUST support high security. Service provisioning
SHOULD use high security, subject to local security policies. SHOULD use high security, subject to local security policies.
11.2 Client-to-Server Communications 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 provides a reliable mechanism for helping to ensure the
confidentiality and data integrity of data exchanged between two confidentiality and data integrity of data exchanged between two
entities. entities.
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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 [31]. End-to-End Object Encryption in XMPP [32].
11.3 Server-to-Server Communications 11.3 Server-to-Server Communications
A compliant implementation MUST support both TLS and SASL for inter- A compliant implementation MUST support both TLS and SASL for
domain communications. For historical reasons, a compliant inter-domain communications. For historical reasons, a compliant
implementation SHOULD also support the lower-security Dialback implementation SHOULD also support the lower-security Dialback
Protocol (Section 6.2), which provides a mechanism for helping to Protocol (Section 6.2), which provides a mechanism for helping to
prevent the spoofing of domains. prevent the spoofing of domains.
Because service provisioning is a matter of policy, it is OPTIONAL Because service provisioning is a matter of policy, it is OPTIONAL
for any given domain to communicate with other domains, and server- for any given domain to communicate with other domains, and
to-server communications MAY be disabled by the administrator of any server-to-server communications MAY be disabled by the administrator
given deployment. If a particular domain enables inter-domain of any given deployment. If a particular domain enables inter-domain
communications, it SHOULD enable high security. In the absence of communications, it SHOULD enable high security. In the absence of
high security, a domain MAY use server dialback for inter-domain high security, a domain MAY use server dialback for inter-domain
communications. communications.
Administrators may want to require use of SASL for server-to-server Administrators may want to require use of SASL for server-to-server
communications in order to ensure authentication and confidentiality communications in order to ensure authentication and confidentiality
(e.g., on an organization's private network). Compliant (e.g., on an organization's private network). Compliant
implementations SHOULD support SASL for this purpose. implementations SHOULD support SASL for this purpose.
11.4 Firewalls 11.4 Firewalls
skipping to change at page 61, line 39 skipping to change at page 61, line 39
Support", STD 3, RFC 1123, October 1989. Support", STD 3, RFC 1123, October 1989.
[8] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile [8] 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.
[9] Hoffman, P. and M. Blanchet, "Preparation of Internationalized [9] Hoffman, P. and M. Blanchet, "Preparation of Internationalized
Strings ("stringprep")", RFC 3454, December 2002. Strings ("stringprep")", RFC 3454, December 2002.
[10] Saint-Andre, P. and J. Hildebrand, "Nodeprep: A Stringprep [10] Saint-Andre, P. and J. Hildebrand, "Nodeprep: A Stringprep
Profile for Node Identifiers in XMPP (draft-ietf-xmpp-nodeprep- Profile for Node Identifiers in XMPP
02, work in progress)", April 2003. (draft-ietf-xmpp-nodeprep-02, work in progress)", April 2003.
[11] Saint-Andre, P. and J. Hildebrand, "Resourceprep: A Stringprep [11] Saint-Andre, P. and J. Hildebrand, "Resourceprep: A Stringprep
Profile for Resource Identifiers in XMPP (draft-ietf-xmpp- Profile for Resource Identifiers in XMPP
resourceprep-02, work in progress)", April 2003. (draft-ietf-xmpp-resourceprep-02, work in progress)", April
2003.
[12] World Wide Web Consortium, "Namespaces in XML", W3C xml-names, [12] World Wide Web Consortium, "Namespaces in XML", W3C xml-names,
January 1999, <http://www.w3.org/TR/1999/REC-xml-names- January 1999, <http://www.w3.org/TR/1999/
19990114/>. REC-xml-names-19990114/>.
[13] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and [13] 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.
[14] Myers, J., "Simple Authentication and Security Layer (SASL)", [14] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[15] Myers, J., "Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997. RFC 2222, October 1997.
[15] Leach, P. and C. Newman, "Using Digest Authentication as a SASL [16] Leach, P. and C. Newman, "Using Digest Authentication as a SASL
Mechanism", RFC 2831, May 2000. Mechanism", RFC 2831, May 2000.
[16] Alvestrand, H., "Tags for the Identification of Languages", BCP [17] Alvestrand, H., "Tags for the Identification of Languages", BCP
47, RFC 3066, January 2001. 47, RFC 3066, January 2001.
[17] Gulbrandsen, A. and P. Vixie, "A DNS RR for specifying the [18] Gulbrandsen, A. and P. Vixie, "A DNS RR for specifying the
location of services (DNS SRV)", RFC 2052, October 1996. location of services (DNS SRV)", RFC 2052, October 1996.
[18] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC [19] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998. 2279, January 1998.
[19] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646", [20] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646",
RFC 2781, February 2000. RFC 2781, February 2000.
[20] International Organization for Standardization, "Information [21] International Organization for Standardization, "Information
Technology - Universal Multiple-octet coded Character Set (UCS) Technology - Universal Multiple-octet coded Character Set (UCS)
- Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO - Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO
Standard 10646-1 Addendum 2, October 1996. Standard 10646-1 Addendum 2, October 1996.
[21] Linn, J., "Generic Security Service Application Program [22] Linn, J., "Generic Security Service Application Program
Interface, Version 2", RFC 2078, January 1997. Interface, Version 2", RFC 2078, January 1997.
Informative References Informative References
[22] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging (draft- [23] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging
ietf-xmpp-im-09, work in progress)", April 2003. (draft-ietf-xmpp-im-09, work in progress)", April 2003.
[23] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [24] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, August Resource Identifiers (URI): Generic Syntax", RFC 2396, August
1998, <http://www.ietf.org/rfc/rfc2396.txt>. 1998, <http://www.ietf.org/rfc/rfc2396.txt>.
[24] Mealling, M., "The IANA XML Registry", draft-mealling-iana- [25] Mealling, M., "The IANA XML Registry",
xmlns-registry-04 (work in progress), June 2002. draft-mealling-iana-xmlns-registry-04 (work in progress), June
2002.
[25] Crispin, M., "Internet Message Access Protocol - Version [26] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 2060, December 1996. 4rev1", RFC 2060, December 1996.
[26] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD [27] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD
53, RFC 1939, May 1996. 53, RFC 1939, May 1996.
[27] Newman, C. and J. Myers, "ACAP -- Application Configuration [28] Newman, C. and J. Myers, "ACAP -- Application Configuration
Access Protocol", RFC 2244, November 1997. Access Protocol", RFC 2244, November 1997.
[28] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595, [29] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595,
June 1999. June 1999.
[29] Eastlake, D., "Domain Name System Security Extensions", RFC [30] Eastlake, D., "Domain Name System Security Extensions", RFC
2535, March 1999. 2535, March 1999.
[30] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., [31] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L.,
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999. HTTP/1.1", RFC 2616, June 1999.
[31] Saint-Andre, P. and J. Hildebrand, "End-to-End Object [32] Saint-Andre, P. and J. Hildebrand, "End-to-End Object
Encryption in XMPP (draft-ietf-xmpp-e2e-02, work in progress)", Encryption in XMPP (draft-ietf-xmpp-e2e-02, work in progress)",
April 2003. April 2003.
Authors' Addresses Authors' Addresses
Peter Saint-Andre Peter Saint-Andre
Jabber Software Foundation Jabber Software Foundation
EMail: stpeter@jabber.org EMail: stpeter@jabber.org
URI: http://www.jabber.org/people/stpeter.php URI: http://www.jabber.org/people/stpeter.php
skipping to change at page 69, line 25 skipping to change at page 69, line 25
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> </xs:choice>
<xs:attribute name='to' type='xs:string' use='optional'/> <xs:attribute name='to' type='xs:string' use='optional'/>
<xs:attribute name='from' type='xs:string' use='optional'/> <xs:attribute name='from' type='xs:string' use='optional'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/> type='xs:NMTOKEN'
use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='chat'/> <xs:enumeration value='chat'/>
<xs:enumeration value='groupchat'/> <xs:enumeration value='groupchat'/>
<xs:enumeration value='headline'/> <xs:enumeration value='headline'/>
<xs:enumeration value='error'/> <xs:enumeration value='error'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='body' type='xs:string'> <xs:element name='body' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute name='xml:lang' <xs:simpleContent>
type='xmlLangType' use='optional'/> <xs:extension base='xs:NMTOKEN'>
<xs:attribute name='xml:lang' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='subject' type='xs:string'> <xs:element name='subject' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute name='xml:lang' <xs:simpleContent>
type='xmlLangType' use='optional'/> <xs:extension base='xs:NMTOKEN'>
<xs:attribute name='xml:lang' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='thread' type='xs:string'/> <xs:element name='thread' type='xs:string'/>
<xs:element name='presence'> <xs:element name='presence'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:choice maxOccurs='unbounded'>
<xs:element ref='show' minOccurs='0' maxOccurs='1'/> <xs:element ref='show' minOccurs='0' maxOccurs='1'/>
<xs:element ref='status' <xs:element ref='status'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='priority' minOccurs='0' maxOccurs='1'/> <xs:element ref='priority' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
skipping to change at page 70, line 23 skipping to change at page 70, line 31
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> </xs:choice>
<xs:attribute name='to' type='xs:string' use='optional'/> <xs:attribute name='to' type='xs:string' use='optional'/>
<xs:attribute name='from' type='xs:string' use='optional'/> <xs:attribute name='from' type='xs:string' use='optional'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/> type='xs:NMTOKEN'
use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='subscribe'/> <xs:enumeration value='subscribe'/>
<xs:enumeration value='subscribed'/> <xs:enumeration value='subscribed'/>
<xs:enumeration value='unsubscribe'/> <xs:enumeration value='unsubscribe'/>
<xs:enumeration value='unsubscribed'/> <xs:enumeration value='unsubscribed'/>
<xs:enumeration value='unavailable'/> <xs:enumeration value='unavailable'/>
<xs:enumeration value='error'/> <xs:enumeration value='error'/>
</xs:restriction> </xs:restriction>
skipping to change at page 71, line 4 skipping to change at page 71, line 13
<xs:enumeration value='away'/> <xs:enumeration value='away'/>
<xs:enumeration value='chat'/> <xs:enumeration value='chat'/>
<xs:enumeration value='xa'/> <xs:enumeration value='xa'/>
<xs:enumeration value='dnd'/> <xs:enumeration value='dnd'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:element> </xs:element>
<xs:element name='status' type='xs:string'> <xs:element name='status' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute name='xml:lang' <xs:simpleContent>
type='xmlLangType' use='optional'/> <xs:extension base='xs:NMTOKEN'>
<xs:attribute name='xml:lang' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='priority' type='xs:byte'/> <xs:element name='priority' type='xs:byte'/>
<xs:element name='iq'> <xs:element name='iq'>
<xs:complexType> <xs:complexType>
<xs:sequence> <xs:sequence>
<xs:any <xs:any
namespace='##other' namespace='##other'
skipping to change at page 72, line 4 skipping to change at page 72, line 16
<xs:enumeration value='address'/> <xs:enumeration value='address'/>
<xs:enumeration value='app'/> <xs:enumeration value='app'/>
<xs:enumeration value='format'/> <xs:enumeration value='format'/>
<xs:enumeration value='recipient'/> <xs:enumeration value='recipient'/>
<xs:enumeration value='server'/> <xs:enumeration value='server'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:simpleType name="xmlLangType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[a-z]{2}-[A-Z]{2}"/>
</xs:restriction>
</xs:simpleType>
</xs:schema> </xs:schema>
A.6 Server namespace A.6 Server namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='http://www.jabber.org/protocol' targetNamespace='jabber:server'
xmlns='http://www.jabber.org/protocol' xmlns='jabber:server'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='message'> <xs:element name='message'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:choice maxOccurs='unbounded'>
<xs:element ref='body' <xs:element ref='body'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='subject' <xs:element ref='subject'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='thread' minOccurs='0' maxOccurs='1'/> <xs:element ref='thread' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> </xs:choice>
<xs:attribute name='to' type='xs:string' use='required'/> <xs:attribute name='to' type='xs:string' use='required'/>
<xs:attribute name='from' type='xs:string' use='required'/> <xs:attribute name='from' type='xs:string' use='required'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/> type='xs:NMTOKEN'
use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='chat'/> <xs:enumeration value='chat'/>
<xs:enumeration value='groupchat'/> <xs:enumeration value='groupchat'/>
<xs:enumeration value='headline'/> <xs:enumeration value='headline'/>
<xs:enumeration value='error'/> <xs:enumeration value='error'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='body' type='xs:string'> <xs:element name='body' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute name='xml:lang' <xs:simpleContent>
type='xmlLangType' use='optional'/> <xs:extension base='xs:NMTOKEN'>
<xs:attribute name='xml:lang' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='subject' type='xs:string'> <xs:element name='subject' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute name='xml:lang' <xs:simpleContent>
type='xmlLangType' use='optional'/> <xs:extension base='xs:NMTOKEN'>
<xs:attribute name='xml:lang' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='thread' type='xs:string'/> <xs:element name='thread' type='xs:string'/>
<xs:element name='presence'> <xs:element name='presence'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:choice maxOccurs='unbounded'>
<xs:element ref='show' minOccurs='0' maxOccurs='1'/> <xs:element ref='show' minOccurs='0' maxOccurs='1'/>
<xs:element ref='status' <xs:element ref='status'
skipping to change at page 73, line 40 skipping to change at page 74, line 6
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> </xs:choice>
<xs:attribute name='to' type='xs:string' use='required'/> <xs:attribute name='to' type='xs:string' use='required'/>
<xs:attribute name='from' type='xs:string' use='required'/> <xs:attribute name='from' type='xs:string' use='required'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/> type='xs:NMTOKEN'
use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='subscribe'/> <xs:enumeration value='subscribe'/>
<xs:enumeration value='subscribed'/> <xs:enumeration value='subscribed'/>
<xs:enumeration value='unsubscribe'/> <xs:enumeration value='unsubscribe'/>
<xs:enumeration value='unsubscribed'/> <xs:enumeration value='unsubscribed'/>
<xs:enumeration value='unavailable'/> <xs:enumeration value='unavailable'/>
<xs:enumeration value='error'/> <xs:enumeration value='error'/>
</xs:restriction> </xs:restriction>
skipping to change at page 74, line 21 skipping to change at page 74, line 36
<xs:enumeration value='away'/> <xs:enumeration value='away'/>
<xs:enumeration value='chat'/> <xs:enumeration value='chat'/>
<xs:enumeration value='xa'/> <xs:enumeration value='xa'/>
<xs:enumeration value='dnd'/> <xs:enumeration value='dnd'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:element> </xs:element>
<xs:element name='status' type='xs:string'> <xs:element name='status' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute name='xml:lang' <xs:simpleContent>
type='xmlLangType' use='optional'/> <xs:extension base='xs:NMTOKEN'>
<xs:attribute name='xml:lang' use='optional'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='priority' type='xs:byte'/> <xs:element name='priority' type='xs:byte'/>
<xs:element name='iq'> <xs:element name='iq'>
<xs:complexType> <xs:complexType>
<xs:sequence> <xs:sequence>
<xs:any <xs:any
namespace='##other' namespace='##other'
skipping to change at page 75, line 21 skipping to change at page 75, line 40
<xs:enumeration value='app'/> <xs:enumeration value='app'/>
<xs:enumeration value='format'/> <xs:enumeration value='format'/>
<xs:enumeration value='recipient'/> <xs:enumeration value='recipient'/>
<xs:enumeration value='server'/> <xs:enumeration value='server'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:simpleType name="xmlLangType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[a-z]{2}-[A-Z]{2}"/>
</xs:restriction>
</xs:simpleType>
</xs:schema> </xs:schema>
A.7 Stream error namespace A.7 Stream error namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='urn:ietf:params:xml:ns:xmpp-streams' targetNamespace='urn:ietf:params:xml:ns:xmpp-streams'
xmlns='urn:ietf:params:xml:ns:xmpp-streams' xmlns='urn:ietf:params:xml:ns:xmpp-streams'
skipping to change at page 78, line 14 skipping to change at page 78, line 14
Appendix B. Revision History Appendix B. 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.
B.1 Changes from draft-ietf-xmpp-core-09 B.1 Changes from draft-ietf-xmpp-core-09
o Fixed several dialback error conditions. o Fixed several dialback error conditions.
o Cleaned up business rules regarding TLS and certificate processing
based on off-list feedback.
o Changed <stream-condition/> and <stanza-condition/> elements to o Changed <stream-condition/> and <stanza-condition/> elements to
<condition/>. <condition/>.
o Added or modified several stream and stanza error conditions. o Added or modified several stream and stanza error conditions.
o Specified only one child allowed for IQ, or two if type="error". o Specified only one child allowed for IQ, or two if type="error".
o Fixed several errors in the schemas.
B.2 Changes from draft-ietf-xmpp-core-08 B.2 Changes from draft-ietf-xmpp-core-08
o Incorporated list discussion regarding addressing, SASL, TLS, TCP, o Incorporated list discussion regarding addressing, SASL, TLS, TCP,
dialback, namespaces, extensibility, and the meaning of 'ignore' dialback, namespaces, extensibility, and the meaning of 'ignore'
for routers and recipients. for routers and recipients.
o Specified dialback error conditions. o Specified dialback error conditions.
o Made small editorial changes to address RFC Editor requirements. o Made small editorial changes to address RFC Editor requirements.
skipping to change at page 78, line 46 skipping to change at page 79, line 6
o Added text regarding certificate validation in TLS negotiation per o Added text regarding certificate validation in TLS negotiation per
list discussion. list discussion.
o Clarified nature of XML restrictions per discussion with W3C, and o Clarified nature of XML restrictions per discussion with W3C, and
moved XML Restrictions subsection under "XML Usage within XMPP". moved XML Restrictions subsection under "XML Usage within XMPP".
o Further clarified that XML streams are unidirectional. o Further clarified that XML streams are unidirectional.
o Changed stream error and stanza error namespace names to conform o Changed stream error and stanza error namespace names to conform
to the format defined in The IETF XML Registry [24]. to the format defined in The IETF XML Registry [25].
o Removed note to RFC Editor regarding provisional namespace names. o Removed note to RFC Editor regarding provisional namespace names.
B.5 Changes from draft-ietf-xmpp-core-05 B.5 Changes from draft-ietf-xmpp-core-05
o Added <invalid-namespace/> as a stream error condition. o Added <invalid-namespace/> as a stream error condition.
o Adjusted security considerations per discussion at IETF 56 and on o Adjusted security considerations per discussion at IETF 56 and on
list. list.
skipping to change at page 82, line 5 skipping to change at page 82, 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).
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Acknowledgement Acknowledgement
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