draft-ietf-xmpp-core-08.txt   draft-ietf-xmpp-core-09.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft J. Miller Internet-Draft J. Miller
Expires: October 6, 2003 Jabber Software Foundation Expires: October 16, 2003 Jabber Software Foundation
April 7, 2003 April 17, 2003
XMPP Core XMPP Core
draft-ietf-xmpp-core-08 draft-ietf-xmpp-core-09
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . 8 3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . 8
3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . . 8 3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . 8
3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . 8
3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . . 9 3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . 9
4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . 10 4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2 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 . . . . . . . . . . . . . . . . . . . . . . . 13 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 . . . . . . . . . . . . . . . . . . . . . 18 5. Stream Encryption . . . . . . . . . . . . . . . . . . . . 19
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 20
5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . . 20 5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . 21
5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . . 21 5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . 23
6. Stream Authentication . . . . . . . . . . . . . . . . . . . 24 6. Stream Authentication . . . . . . . . . . . . . . . . . . 26
6.1 SASL Authentication . . . . . . . . . . . . . . . . . . . . 24 6.1 SASL Authentication . . . . . . . . . . . . . . . . . . . 26
6.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 24 6.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 26 6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . 29
6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . . 27 6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . 30
6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . . 29 6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . 32
6.2 Dialback Authentication . . . . . . . . . . . . . . . . . . 31 6.2 Dialback Authentication . . . . . . . . . . . . . . . . . 35
6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . . 34 6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . 37
7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 37 7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . 42
7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . . 37 7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . 42
7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . . 38 7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . 44
7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . . 39 7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . 44
7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 39 7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . . 40 7.3.2.1 Body . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . . 41 7.3.2.2 Subject . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7.3.2.3 Thread . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . 46
7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . 46
7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . . 43 7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.4.2.1 Show . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . . 44 7.4.2.2 Status . . . . . . . . . . . . . . . . . . . . . . . . . . 47
7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 45 7.4.2.3 Priority . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 48
7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 46 7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . 49
7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 47 7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . 49
8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 48 7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . 49
8.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 48 7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . 50
8.2 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 50
8.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.4 Character Encodings . . . . . . . . . . . . . . . . . . . . 49 7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . 52
8.5 Inclusion of Text Declaration . . . . . . . . . . . . . . . 49 7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . 53
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 50 8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . 54
9.1 XML Namespace Name for Stream Errors . . . . . . . . . . . . 50 8.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . 54
9.2 XML Namespace Name for Stanza Errors . . . . . . . . . . . . 50 8.2 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . 54
9.3 Existing Registrations . . . . . . . . . . . . . . . . . . . 50 8.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . 54
10. Internationalization Considerations . . . . . . . . . . . . 51 8.4 Character Encodings . . . . . . . . . . . . . . . . . . . 55
11. Security Considerations . . . . . . . . . . . . . . . . . . 52 8.5 Inclusion of Text Declaration . . . . . . . . . . . . . . 55
11.1 High Security . . . . . . . . . . . . . . . . . . . . . . . 52 9. IANA Considerations . . . . . . . . . . . . . . . . . . . 56
11.2 Client-to-Server Communications . . . . . . . . . . . . . . 52 9.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . 56
11.3 Server-to-Server Communications . . . . . . . . . . . . . . 52 9.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . 56
11.4 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . 53 9.3 XML Namespace Name for Stream Errors . . . . . . . . . . . 56
11.5 Mandatory to Implement Technologies . . . . . . . . . . . . 53 9.4 XML Namespace Name for Stanza Errors . . . . . . . . . . . 57
References . . . . . . . . . . . . . . . . . . . . . . . . . 54 9.5 Existing Registrations . . . . . . . . . . . . . . . . . . 57
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 56 10. Internationalization Considerations . . . . . . . . . . . 58
A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 57 11. Security Considerations . . . . . . . . . . . . . . . . . 59
A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . . 57 11.1 High Security . . . . . . . . . . . . . . . . . . . . . . 59
A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 58 11.2 Client-to-Server Communications . . . . . . . . . . . . . 59
A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 58 11.3 Server-to-Server Communications . . . . . . . . . . . . . 60
A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 59 11.4 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . 60
A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . . 60 11.5 Mandatory to Implement Technologies . . . . . . . . . . . 60
A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . . 63 Normative References . . . . . . . . . . . . . . . . . . . 61
A.7 Stream error namespace . . . . . . . . . . . . . . . . . . . 66 Informative References . . . . . . . . . . . . . . . . . . 63
A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . . 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . 63
B. Revision History . . . . . . . . . . . . . . . . . . . . . . 69 A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . 65
B.1 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . . 69 A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . 65
B.2 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . . 69 A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . 66
B.3 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . . 69 A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . 66
B.4 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 69 A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . 67
B.5 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 70 A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . 68
B.6 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 70 A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . 72
B.7 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 70 A.7 Stream error namespace . . . . . . . . . . . . . . . . . . 75
B.8 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 70 A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . 76
B.9 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 71 B. Revision History . . . . . . . . . . . . . . . . . . . . . 78
Intellectual Property and Copyright Statements . . . . . . . 72 B.1 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . 78
B.2 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . 78
B.3 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . 78
B.4 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . 78
B.5 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . 79
B.6 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . 79
B.7 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . 79
B.8 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . 79
B.9 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . 80
B.10 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 [1] protocol for near-real-time messaging, presence, and request-
request-response services. The basic syntax and semantics were response services. The basic syntax and semantics were developed
developed originally within the Jabber open-source community, mainly originally within the Jabber open-source community, mainly in 1999.
in 1999. In 2002, the XMPP WG was chartered with developing an In 2002, the XMPP WG was chartered with developing an adaptation of
adaptation of the Jabber protocol that would be suitable as an IETF the Jabber protocol that would be suitable as an IETF instant
instant messaging and presence technology. As a result of work by the messaging and presence technology. As a result of work by the XMPP
XMPP WG, the current document defines the core features of XMPP; XMPP WG, the current document defines the core features of XMPP; XMPP IM
IM [2] defines the extensions required to provide the instant [22] defines the extensions required to provide the instant messaging
messaging (IM) and presence functionality defined in RFC 2779 [3]. (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 [4]. 2119 [3].
1.3 Discussion Venue 1.3 Discussion Venue
The authors welcome discussion and comments related to the topics The authors welcome discussion and comments related to the topics
presented in this document. The preferred forum is the presented in this document. The preferred forum is the
<xmppwg@jabber.org> mailing list, for which archives and subscription <xmppwg@jabber.org> mailing list, for which archives and subscription
information are available at <http://www.jabber.org/cgi-bin/mailman/ information are available at <http://www.jabber.org/cgi-bin/mailman/
listinfo/xmppwg/>. listinfo/xmppwg/>.
1.4 Intellectual Property Notice 1.4 Intellectual Property Notice
skipping to change at page 6, line 10 skipping to change at page 6, line 10
identifying namespaces and other protocol syntax. Jabber[tm] is a identifying namespaces and other protocol syntax. Jabber[tm] is a
registered trademark of Jabber, Inc. Jabber, Inc. grants permission registered trademark of Jabber, Inc. Jabber, Inc. grants permission
to the IETF for use of the Jabber trademark in association with this to the IETF for use of the Jabber trademark in association with this
specification and its successors, if any. specification and its successors, if any.
2. Generalized Architecture 2. Generalized Architecture
2.1 Overview 2.1 Overview
Although XMPP is not wedded to any specific network architecture, to Although XMPP is not wedded to any specific network architecture, to
this point it has usually been implemented via a typical this point it has usually been implemented via a typical client-
client-server architecture, wherein a client utilizing XMPP accesses server architecture, wherein a client utilizing XMPP accesses a
a server over a TCP [5] socket. 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 4 skipping to change at page 7, line 6
and to route appropriately-addressed XML data "stanzas" among such and to route appropriately-addressed XML data "stanzas" among such
entities over XML streams. Most XMPP-compliant servers also assume entities over XML streams. Most XMPP-compliant servers also assume
responsibility for the storage of data that is used by clients (e.g., responsibility for the storage of data that is used by clients (e.g.,
contact lists for users of XMPP-based IM applications); in this case, contact lists for users of XMPP-based IM applications); in this case,
the XML data is processed directly by the server itself on behalf of the XML data is processed directly by the server itself on behalf of
the client and is not routed to another entity. Compliant server the client and is not routed to another entity. Compliant server
implementations MUST ensure in-order processing of XML stanzas implementations MUST ensure in-order processing of XML stanzas
between any two entities. between any two entities.
2.3 Client 2.3 Client
Most clients connect directly to a server over a TCP socket and use Most clients connect directly to a server over a TCP socket and use
XMPP to take full advantage of the functionality provided by a server XMPP to take full advantage of the functionality provided by a server
and any associated services, although it must be noted that there is and any associated services. Although there is no necessary coupling
no necessary coupling of an XML stream to a TCP socket (e.g., a of an XML stream to a TCP socket (e.g., a client COULD connect via
client COULD connect via HTTP polling or some other mechanism). HTTP polling or some other mechanism), this specification defines a
Multiple resources (e.g., devices or locations) MAY connect binding for XMPP to TCP only. Multiple resources (e.g., devices or
simultaneously to a server on behalf of each authorized client, with locations) MAY connect simultaneously to a server on behalf of each
each resource connecting over a discrete TCP socket and authorized client, with each resource connecting over a discrete TCP
differentiated by the resource identifier of a JID (Section 3) (e.g., socket and differentiated by the resource identifier of a JID
user@domain/home vs. user@domain/work). The port registered with the (Section 3) (e.g., user@domain/home vs. user@domain/work). The port
IANA [6] for connections between a Jabber client and a Jabber server registered with the IANA [5] for connections between a Jabber client
is 5222. For further details about client-to-server communications and a Jabber server is 5222.
expressly for the purpose of instant messaging and presence, refer to
XMPP IM [2].
2.4 Gateway 2.4 Gateway
A gateway is a special-purpose server-side service whose primary A gateway is a special-purpose server-side service whose primary
function is to translate XMPP into the protocol(s) of another function is to translate XMPP into the protocol used by a foreign
messaging system, as well as to translate the return data back into (non-XMPP) messaging system, as well as to translate the return data
XMPP. Examples are gateways to SIMPLE, Internet Relay Chat (IRC), back into XMPP. Examples are gateways to SIMPLE, Internet Relay Chat
Short Message Service (SMS), SMTP, and foreign instant messaging (IRC), Short Message Service (SMS), SMTP, and legacy instant
networks such as Yahoo!, MSN, ICQ, and AIM. Communications between messaging networks such as AIM, ICQ, MSN Messenger, and Yahoo!
gateways and servers, and between gateways and the foreign messaging Instant Messenger. Communications between gateways and servers, and
system, are not defined in this document. between gateways and the foreign messaging system, are not defined in
this document.
2.5 Network 2.5 Network
Because each server is identified by a network address (typically a Because each server is identified by a network address (typically a
DNS hostname) and because server-to-server communications are a DNS hostname) and because server-to-server communications are a
straightforward extension of the client-to-server protocol, in straightforward extension of the client-to-server protocol, in
practice the system consists of a network of servers that practice the system consists of a network of servers that inter-
inter-communicate. Thus user-a@domain1 is able to exchange messages, communicate. Thus user-a@domain1 is able to exchange messages,
presence, and other information with user-b@domain2. This pattern is presence, and other information with user-b@domain2. This pattern is
familiar from messaging protocols (such as SMTP) that make use of familiar from messaging protocols (such as SMTP) that make use of
network addressing standards. Upon opening a TCP socket on the network addressing standards. Upon opening a TCP socket on the IANA-
IANA-registered port 5269, there are two methods for negotiating a registered port 5269, there are two methods for negotiating a
connection between any two servers: server dialback (Section 6.2) and connection between any two servers: primarily SASL authentication
SASL authentication (Section 6.1). (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. All (i.e., an ID on the network) and that can communicate using XMPP.
such entities are uniquely addressable in a form that is consistent All such entities are uniquely addressable in a form that is
with RFC 2396 [7]. In particular, a valid Jabber Identifier (JID) consistent with RFC 2396 [23]. In particular, a valid Jabber
contains a set of ordered elements formed of a domain identifier, Identifier (JID) contains a set of ordered elements formed of a
node identifier, and resource identifier in the following format: domain identifier, node identifier, and resource identifier in the
[node@]domain[/resource]. following format: [node@]domain[/resource].
All JIDs are based on the foregoing structure. The most common use of All JIDs are based on the foregoing structure. The most common use
this structure is to identify an IM user, the server to which the of this structure is to identify an IM user, the server to which the
user connects, and the user's active session or connection (e.g., a user connects, and the user's active session or connection (e.g., a
specific client) in the form of user@domain/resource. However, node specific client) in the form of user@domain/resource. However, node
types other than clients are possible; for example, a specific chat types other than clients are possible; for example, a specific chat
room offered by a multi-user chat service could be addressed as room offered by a multi-user chat service could be addressed as
<room@service> (where "room" is the name of the chat room and <room@service> (where "room" is the name of the chat room and
"service" is the hostname of the multi-user chat service) and a "service" is the hostname of the multi-user chat service) and a
specific occupant of such a room could be addressed as <room@service/ specific occupant of such a room could be addressed as <room@service/
nick> (where "nick" is the occupant's room nickname). Many other JID nick> (where "nick" is the occupant's room nickname). Many other JID
types are possible (e.g., <domain/resource> could be a server-side types are possible (e.g., <domain/resource> could be a server-side
script or service). script or service).
skipping to change at page 8, line 44 skipping to change at page 8, line 44
It usually represents the network gateway or "primary" server to It usually represents the network gateway or "primary" server to
which other entities connect for XML routing and data management which other entities connect for XML routing and data management
capabilities. However, the entity referenced by a domain identifier capabilities. However, the entity referenced by a domain identifier
is not always a server, and may be a service that is addressed as a is not always a server, and may be a service that is addressed as a
subdomain of a server and that provides functionality above and subdomain of a server and that provides functionality above and
beyond the capabilities of a server (a multi-user chat service, a beyond the capabilities of a server (a multi-user chat service, a
user directory, a gateway to a foreign messaging system, etc.). user directory, a gateway to a foreign messaging system, etc.).
The domain identifier for every server or service that will The domain identifier for every server or service that will
communicate over a network SHOULD resolve to a Fully Qualified Domain communicate over a network SHOULD resolve to a Fully Qualified Domain
Name. A domain identifier MUST conform to RFC 952 [8] and RFC 1123 Name. A domain identifier MUST conform to RFC 952 [6] and RFC 1123
[9]. 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 [10] profile of stringprep [11]. 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 by associated with a multi-user chat service). The entity represented
a node identifier is addressed within the context of a specific by a node identifier is addressed within the context of a specific
domain; within IM applications of XMPP this address is called a "bare domain; within IM applications of XMPP this address is called a "bare
JID" and is of the form <user@domain>. JID" and is of the form <user@domain>.
A node identifier MUST be no more than 1023 bytes in length and MUST A node identifier MUST be no more than 1023 bytes in length and MUST
conform to the nodeprep [12] profile of stringprep [11]. conform to the nodeprep [10] profile of stringprep [9].
3.4 Resource Identifier 3.4 Resource Identifier
The resource identifer is an optional tertiary identifier. It usually The resource identifier is an optional tertiary identifier, which may
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. An entity belonging to the entity associated with a node identifier. A
may maintain multiple resources simultaneously. resource identifier is typically defined by a client implementation
and is opaque to both servers and other clients. An entity may
maintain multiple resources simultaneously.
A resource identifier MUST be no more than 1023 bytes in length and A resource identifier MUST be no more than 1023 bytes in length and
MUST conform to the resourceprep [13] profile of stringprep [11]. 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: between presence-aware entities: XML streams and XML stanzas. The
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. An XML stream corresponds to the normally over a TCP socket, and corresponds to the initiating
initiating entity's "session" with the receiving entity. The start entity's "session" with the receiving entity. The start of the
of the XML stream is denoted unambiguously by an opening XML XML stream is denoted unambiguously by an opening XML <stream> tag
<stream> tag with appropriate attributes and namespace with appropriate attributes and namespace declarations, and the
declarations, and the end of the XML stream is denoted end of the XML stream is denoted unambiguously be a closing XML </
unambiguously be a closing XML </stream> tag. An XML stream is stream> tag. An XML stream is unidirectional; in order to enable
unidirectional; in order to enable bidirectional information bidirectional information exchange, the initiating entity and
exchange, one stream must be negotiated from initiating entity to receiving entity must negotiate one stream in each direction,
receiving entity and another stream must be negotiated from normally over the same TCP connection.
receiving entity to initiating entity.
Definition of XML stanza: An XML stanza is a discrete semantic unit Definition of XML stanza: An XML stanza is a discrete semantic unit
of structured information that is sent from one entity to another of structured information that is sent from one entity to another
over an XML stream. An XML stanza exists at the direct child level over an XML stream. An XML stanza exists at the direct child
of the root <stream/> element and is said to be well-balanced if level of the root <stream/> element and is said to be well-
it matches production [43] content of the XML specification [1]). balanced if it matches production [43] content of the XML
The start of any XML stanza is denoted unambiguously by the specification [1]). The start of any XML stanza is denoted
element start tag at depth=1 (e.g., <presence>), and the end of unambiguously by the element start tag at depth=1 (e.g.,
any XML stanza is denoted unambiguously by the corresponding close <presence>), and the end of any XML stanza is denoted
tag at depth=1 (e.g., </presence>). An XML stanza MAY contain unambiguously by the corresponding close tag at depth=1 (e.g., </
child elements (with accompanying attributes, elements, and CDATA) presence>). An XML stanza MAY contain child elements (with
as necessary in order to convey the desired information. accompanying attributes, elements, and CDATA) as necessary in
order to convey the desired information.
Consider the example of a client's session with a server. In order to Consider the example of a client's session with a server. In order
connect to a server, a client must initiate an XML stream by sending to connect to a server, a client must initiate an XML stream by
an opening <stream> tag to the server, optionally preceded by a text sending an opening <stream> tag to the server, optionally preceded by
declaration specifying the XML version supported and the character a text declaration specifying the XML version supported and the
encoding. The server SHOULD then reply with a second XML stream back character encoding. The server SHOULD then reply with a second XML
to the client, again optionally preceded by a text declaration. Once stream back to the client, again optionally preceded by a text
the client has authenticated with the server (see Section 6), the declaration. Once the client has authenticated with the server (see
client MAY send an unlimited number of XML stanzas over the stream to Section 6), the client MAY send an unlimited number of XML stanzas
any recipient on the network. When the client desired to close the over the stream to any recipient on the network. When the client
stream, it simply sends a closing </stream> tag to the server desires to close the stream, it simply sends a closing </stream> tag
(alternatively, the session may be closed by the server). to the server (alternatively, the session may be closed by the
server), after which both the client and server SHOULD close the
underlying TCP connection as well.
Thus a client's session with a server can be seen as two open-ended Those who are accustomed to thinking of XML in a document-centric
XML documents that are built up through the accumulation of the XML manner may wish to view a client's session with a server as
stanzas sent over the two XML streams (i.e., 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), and the root the server and one from the server to the client. From this
<stream/> element can be considered the document entity for each perspective, the root <stream/> element can be considered the
document. In essence, then, an XML stream acts as an envelope for all document entity for each "document", and the two "documents" are
the XML stanzas sent during a session. We can represent this built up through the accumulation of XML stanzas sent over the two
graphically as follows: XML streams. However, this perspective is a convenience only, and
XMPP does not deal in documents but in XML streams and XML stanzas.
In essence, then, an XML stream acts as an envelope for all the XML
stanzas sent during a session. We can represent this graphically as
follows:
|-------------------| |-------------------|
| <stream> | | <stream> |
|-------------------| |-------------------|
| <message to=''> | | <message to=''> |
| <body/> | | <body/> |
| </message> | | </message> |
|-------------------| |-------------------|
| <presence to=''> | | <presence to=''> |
| <show/> | | <show/> |
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| ... | | ... |
|-------------------| |-------------------|
| </stream> | | </stream> |
|-------------------| |-------------------|
4.2 Stream Attributes 4.2 Stream Attributes
The attributes of the stream element are as follows: The attributes of the stream element are as follows:
o to -- The 'to' attribute SHOULD be used only in the XML stream o to -- The 'to' attribute SHOULD be used only in the XML stream
from the initiating entity to the receiving entity, and MUST be header from the initiating entity to the receiving entity, and
set to the XMPP address of the receiving entity. There SHOULD be MUST be set to the XMPP address of the receiving entity. There
no 'to' attribute set in the XML stream by which the receiving SHOULD be no 'to' attribute set in the XML stream header by which
entity replies to the initiating entity; however, if a 'to' the receiving entity replies to the initiating entity; however, if
attribute is included, it SHOULD be ignored by the initiating a 'to' attribute is included, it SHOULD be silently ignored by the
entity. initiating entity.
o from -- The 'from' attribute SHOULD be used only in the XML stream o from -- The 'from' attribute SHOULD be used only in the XML stream
from the receiving entity to the initiating entity, and MUST be header from the receiving entity to the initiating entity, and
set to the XMPP address of the receiving entity granting access to MUST be set to the XMPP address of the receiving entity granting
the initiating entity. There SHOULD be no 'from' attribute on the access to the initiating entity. There SHOULD be no 'from'
XML stream sent from the initiating entity to the receiving attribute on the XML stream header sent from the initiating entity
entity; however, if a 'from' attribute is included, it SHOULD be to the receiving entity; however, if a 'from' attribute is
ignored by the receiving entity. included, it SHOULD be silently ignored by the receiving entity.
o id -- The 'id' attribute SHOULD be used only in the XML stream o id -- The 'id' attribute SHOULD be used only in the XML stream
from the receiving entity to the initiating entity. This attribute header from the receiving entity to the initiating entity. This
is a unique identifier created by the receiving entity to function attribute is a unique identifier created by the receiving entity
as a session key for the initiating entity's session with the to function as a session key for the initiating entity's session
receiving entity. There SHOULD be no 'id' attribute on the XML with the receiving entity. There SHOULD be no 'id' attribute on
stream sent from the initiating entity to the receiving entity; the XML stream header sent from the initiating entity to the
however, if an 'id' attribute is included, it SHOULD be ignored by receiving entity; however, if an 'id' attribute is included, it
the receiving entity. SHOULD be silently ignored by the receiving entity.
o version -- The 'version' attribute MAY be used in the XML stream o version -- The 'version' attribute MAY be used in the XML stream
from the initiating entity to the receiving entity in order signal header from the initiating entity to the receiving entity in order
compliance with the protocol defined herein; this is done by signal compliance with the protocol defined herein; this is done
setting the value of the attribute to "1.0". If the initiating by setting the value of the attribute to "1.0". If the initiating
entity includes the version attribute and the receiving entity entity includes the version attribute and the receiving entity
supports XMPP 1.0, the receiving entity MUST reciprocate by supports XMPP 1.0, the receiving entity MUST reciprocate by
including the attribute in its response. including the attribute in its response.
We can summarize these values as follows: We can summarize these values as follows:
| initiating to receiving | receiving to initiating | initiating to receiving | receiving to initiating
------------------------------------------------------------ ------------------------------------------------------------
to | JID of receiver | ignored to | hostname of receiver | silently ignored
from | ignored | JID of receiver from | silently ignored | hostname of receiver
id | ignored | session key id | silently ignored | session key
version | signals XMPP 1.0 support | signals XMPP 1.0 support version | signals XMPP 1.0 support | signals XMPP 1.0 support
4.3 Namespace Declarations 4.3 Namespace Declarations
The stream element MAY contain namespace declarations as defined in The stream element MAY contain namespace declarations as defined in
the XML namespaces specification [14]. the XML namespaces specification [12].
A default namespace declaration ('xmlns') is REQUIRED and is used in
both XML streams in order to scope the allowable first-level children
of the root stream element for both streams. This namespace
declaration MUST be the same for the initiating stream and the
responding stream so that both streams are scoped consistently. The
default namespace declaration applies to the stream and all stanzas
sent within a stream.
A stream namespace declaration (e.g., 'xmlns:stream') is REQUIRED in A stream namespace declaration (e.g., 'xmlns:stream') is REQUIRED in
both XML streams. A compliant entity SHOULD accept any namespace both XML streams. A compliant entity SHOULD accept any namespace
prefix on the <stream/> element; however, for historical reasons some prefix on the <stream/> element; however, for historical reasons some
entities MAY accept only a 'stream' prefix, resulting in the use of a entities MAY accept only a 'stream' prefix, resulting in the use of a
<stream:stream/> element as the stream root. The name of the stream <stream:stream/> element as the stream root. The name of the stream
namespace MUST be "http://etherx.jabber.org/streams". namespace MUST be "http://etherx.jabber.org/streams".
A default namespace declaration ('xmlns') is REQUIRED and is used in
both XML streams in order to define the allowable first-level
children of the root stream element for both streams. This namespace
declaration MUST be the same for the initiating stream and the
responding stream so that both streams are scoped consistently. The
default namespace declaration applies to the stream and all stanzas
sent within a stream (unless explicitly scoped by another namespace).
Since XML streams function as containers for any XML stanzas sent Since XML streams function as containers for any XML stanzas sent
asynchronously between network endpoints, it should be possible to asynchronously between network endpoints, it should be possible to
scope an XML stream with any default namespace declaration (i.e., it scope an XML stream with any default namespace declaration (i.e., it
should be possible to send any properly-namespaced XML stanza over an should be possible to send any properly-namespaced XML stanza over an
XML stream). At a minimum, a compliant implementation MUST support XML stream). At a minimum, a compliant implementation MUST support
the following two namespaces (for historical reasons, existing the following two namespaces (for historical reasons, some
implementations MAY support only these two default namespaces): implementations MAY support only these two default namespaces):
o jabber:client -- this default namespace is declared when the o jabber:client -- this default namespace is declared when the
stream is used for communications between a client and a server stream is used for communications between a client and a server
o jabber:server -- this default namespace is declared when the o jabber:server -- this default namespace is declared when the
stream is used for communications between two servers stream is used for communications between two servers
The jabber:client and jabber:server namespaces are nearly identical The jabber:client and jabber:server namespaces are nearly identical
but are used in different contexts (client-to-server communications but are used in different contexts (client-to-server communications
for jabber:client and server-to-server communications for for jabber:client and server-to-server communications for
jabber:server). The only difference between the two is that the 'to' jabber:server). The only difference between the two is that the 'to'
and 'from' attributes are OPTIONAL on stanzas sent within and 'from' attributes are OPTIONAL on stanzas sent within
jabber:client, whereas they are REQUIRED on stanzas sent within jabber:client, whereas they are REQUIRED on stanzas sent within
jabber:server. If a compliant implementation accepts a stream that is jabber:server. If a compliant implementation accepts a stream that
scoped by the 'jabber:client' or 'jabber:server' namespace, it MUST is scoped by the 'jabber:client' or 'jabber:server' namespace, it
support all three core stanza types (message, presence, and IQ) as MUST support all three core stanza types (message, presence, and IQ)
described herein and defined in the schema. as described herein and defined in the schema.
4.4 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, but stream. Currently this is used for SASL and TLS negotiation only,
it could be used for other negotiable features in the future (usage but it could be used for other negotiable features in the future
is defined under Stream Encryption (Section 5) and Stream (usage is defined under Stream Encryption (Section 5) and Stream
Authentication (Section 6) below). If an entity does not understand Authentication (Section 6) below). If an entity does not understand
or support some features, it SHOULD ignore them. or support some features, it SHOULD 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 Jabber entity (usually a server rather error child MUST be sent by a compliant entity (usually a server
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.
4.5.1 Rules 4.5.1 Rules
The following rules apply to stream-level errors: The following rules apply to stream-level errors:
o It is assumed that all stream-level errors are unrecoverable; o It is assumed that all stream-level errors are unrecoverable;
therefore, if an error occurs at the level of the stream, the therefore, if an error occurs at the level of the stream, the
entity that detects the error MUST send a stream error to the entity that detects the error MUST send a stream error to the
other entity and then send a closing </stream> tag. other entity, send a closing </stream> tag, and close the
underlying TCP connection.
o If the error occurs while the stream is being set up, the o If the error occurs while the stream is being set up, the
receiving entity MUST still send the opening and closing stream receiving entity MUST still send the opening and closing stream
tags and include the error element as a child of the stream tags and include the error element as a child of the stream
element. In this case, if the initiating entity provides an element. In this case, if the initiating entity provides an
unknown host in the 'to' attribute (or provides no 'to' attribute unknown host in the 'to' attribute (or provides no 'to' attribute
at all), the server SHOULD provide the server's authoritative at all), the server SHOULD provide the server's authoritative
hostname in the 'from' attribute of the stream header. hostname in the 'from' attribute of the stream header sent before
termination.
4.5.2 Syntax 4.5.2 Syntax
The syntax for stream errors is as follows: The syntax for stream errors is as follows:
<stream:error class='error-class'> <stream:error class='error-class'>
<stream-condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'> <stream-condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'>
<descriptive-element-name/> <descriptive-element-name/>
</stream-condition> </stream-condition>
</stream:error> </stream:error>
skipping to change at page 14, line 47 skipping to change at page 15, line 9
o format -- the condition relates to XML format or structure o format -- the condition relates to XML format or structure
o redirect -- the condition relates to a host redirection o redirect -- the condition relates to a host redirection
o server -- the condition relates to the internal state of the o server -- the condition relates to the internal state of the
server server
The <stream-condition/> element MUST contain a child element that The <stream-condition/> element MUST contain a child element that
specifies a particular stream-level error condition, as defined in specifies a particular stream-level error condition, as defined in
the next section. (Note: the XML namespace name the next section. (Note: the XML namespace name
'urn:ietf:params:xml:ns:xmpp-streams' that scopes the 'urn:ietf:params:xml:ns:xmpp-streams' that scopes the <stream-
<stream-condition/> element adheres to the format defined in The IETF condition/> element adheres to the format defined in The IETF XML
XML Registry [15].) Registry [24].)
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".
o <host-unknown/> -- the value of the 'to' attribute provided by the o <host-unknown/> -- the value of the 'to' attribute provided by the
initiating entity in the stream header does not correspond to a initiating entity in the stream header does not correspond to a
hostname that is hosted by the server; the associated class is hostname that is hosted by the server; the associated class is
"address". "address".
o <internal-server-error/> -- the server has experienced a o <internal-server-error/> -- the server has experienced a
misconfiguration or an otherwise-undefined internal server error misconfiguration or an otherwise-undefined internal server error
that prevents it from servicing the stream; the associated class that prevents it from servicing the stream; the associated class
is "server". is "server".
o <invalid-id/> -- the stream ID or dialback ID is invalid or does
not match an ID previously provided; the associated class is
"format".
o <invalid-namespace/> -- the stream namespace name is something o <invalid-namespace/> -- the stream namespace name is something
other than "http://etherx.jabber.org/streams"; the associated other than "http://etherx.jabber.org/streams" or the dialback
class is "format". namespace name is something other than "jabber:server:dialback";
the associated class is "format".
o <nonmatching-hosts/> -- the hostname provided in a 'from' address
does not match the hostname (or any validated domain) negotiated
via SASL or dialback; the associated class is "address".
o <remote-connection-failed/> -- the server is unable to properly
connect to a remote resource that is required for authentication
or authorization; the associated class is "server".
o <resource-constraint/> -- the server is resource-contrained and is o <resource-constraint/> -- the server is resource-contrained and is
unable to service the stream; the associated class is "server". unable to service the stream; the associated class is "server".
o <see-other-host/> -- the server will not provide service to the o <see-other-host/> -- the server will not provide service to the
initiating entity but is redirecting traffic to another host; this initiating entity but is redirecting traffic to another host; this
element SHOULD contain CDATA specifying the alternate hostname or element SHOULD contain CDATA specifying the alternate hostname or
IP address to which the initiating entity MAY attempt to connect; IP address to which the initiating entity MAY attempt to connect;
the associated class is "redirect". the associated class is "redirect".
skipping to change at page 16, line 8 skipping to change at page 16, line 31
MAY contain CDATA specifying the XMPP version(s) supported by the MAY contain CDATA specifying the XMPP version(s) supported by the
server; the associated class is "format". server; the associated class is "format".
o <xml-not-well-formed/> -- the initiating entity has sent XML that o <xml-not-well-formed/> -- the initiating entity has sent XML that
is not well-formed as defined by the XML specification [1]; the is not well-formed as defined by the XML specification [1]; the
associated class is "format". associated class is "format".
4.5.4 Extensibility 4.5.4 Extensibility
If desired, an XMPP application MAY provide custom error information; If desired, an XMPP application MAY provide custom error information;
this MUST be contained in a properly-namespaced child of the this MUST be contained in a properly-namespaced child of the <stream-
<stream-condition/> element (i.e., the namespace name MUST NOT be one condition/> element (i.e., the namespace name MUST NOT be one of the
of the namespace names defined herein). namespace names defined herein).
4.6 Simple Streams Example 4.6 Simple Streams Example
The following is a stream-based session of a client on a server The following is a stream-based session of a client on a server
(where the "C" lines are sent from the client to the server, and the (where the "C" lines are sent from the client to the server, and the
"S" lines are sent from the server to the client): "S" lines are sent from the server to the client):
A basic session: A basic session:
C: <?xml version='1.0'?> C: <?xml version='1.0'?>
<stream:stream <stream:stream
to='domain' to='shakespeare.lit'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
S: <?xml version='1.0'?> S: <?xml version='1.0'?>
<stream:stream <stream:stream
from='domain' from='shakespeare.lit'
id='id_123456789' id='id_123456789'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
... authentication ... ... authentication ...
C: <message from='alex@graham-bell' to='watson@graham-bell'> C: <message from='juliet@shakespeare.lit'
C: <body>Watson come here, I want you!</body> to='romeo@shakespeare.lit'>
C: <body>Art thou not Romeo, and a Montague?</body>
C: </message> C: </message>
S: <message from='watson@graham-bell' to='alex@graham-bell'> S: <message from='romeo@shakespeare.lit'
S: <body>I'm on my way!</body> to='juliet@shakespeare.lit'>
S: <body>Neither, fair saint, if either thee dislike.</body>
S: </message> S: </message>
C: </stream:stream> C: </stream:stream>
S: </stream:stream> S: </stream:stream>
These are in actuality a sending stream and a receiving stream, which
can be viewed a-chronologically as two XML documents:
C: <?xml version='1.0'?>
<stream:stream
to='domain'
xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'>
C: <message from='alex@graham-bell' to='watson@graham-bell'>
C: <body>Watson come here, I want you!</body>
C: </message>
C: </stream:stream>
S: <?xml version='1.0'?>
<stream:stream
from='domain'
id='id_123456789'
xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'>
S: <message from='watson@graham-bell' to='alex@graham-bell'>
S: <body>I'm on my way!</body>
S: </message>
S: </stream:stream>
A session gone bad: A session gone bad:
C: <?xml version='1.0'?> C: <?xml version='1.0'?>
<stream:stream <stream:stream
to='server' to='shakespeare.lit'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
S: <?xml version='1.0'?> S: <?xml version='1.0'?>
<stream:stream <stream:stream
from='server' from='shakespeare.lit'
id='id_123456789' id='id_123456789'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
... authentication ...
C: <message><body>Bad XML, no closing body tag!</message> C: <message><body>Bad XML, no closing body tag!</message>
S: <stream:error class='client'> S: <stream:error class='client'>
<stream-condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'> <stream-condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'>
<xml-not-well-formed/> <xml-not-well-formed/>
</stream-condition> </stream-condition>
</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) [16] 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 [17], extension that is modelled on similar extensions for the IMAP [25],
POP3 [18], and ACAP [19] protocols as described in RFC 2595 [20]. The POP3 [26], and ACAP [27] protocols as described in RFC 2595 [28].
namespace identifier for the STARTTLS extension is 'http:// The namespace identifier for the STARTTLS extension is
www.ietf.org/rfc/rfc2595.txt'. TLS SHOULD be used between any 'urn:ietf:params:xml:ns:xmpp-tls'.
initiating entity and any receiving entity (e.g., a stream from a
client to a server or from one server to another).
The following rules MUST be observed: 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
to another). An administrator of a given domain MAY require use of
TLS for either or both client-to-server communications and server-to-
server communications. Servers SHOULD use TLS betweeen two domains
for the purpose of securing server-to-server communcations. When the
remote domain is already known, the server can verify the credentials
of the known domain by comparing known keys or certificates. When
the remote domain is not recognized, it may still be possible to
verify a certificate if it is signed by a common trusted authority.
Even if there is no way to verify certificates (e.g., an unknown
domain with a self-signed certificate, or a certificate signed by an
unrecognized authority), if the servers choose to communicate despite
the lack of verified credentials, TLS still SHOULD be used to provide
encryption.
1. If the initiating entity is capable of using the STARTTLS The following business rules apply:
extension, it MUST include the "version='1.0'" flag in the
initiating stream header.
2. If the receiving entity is capable of using the STARTTLS 1. An initiating entity that complies with this specification MUST
extension, it MUST send the <starttls/> element in the defined include the "version='1.0'" flag in the initiating stream header.
namespace along with the list of features that it sends in
response to the opening stream tag received from the initiating 2. When a receiving entity that complies with this specification
entity. receives an initiating stream header that includes the
"version='1.0'" flag, after sending a stream header in reply it
MUST also send a <starttls/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace as well as the list
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 authenticate the stream using SASL. 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 1. If the initiating entity has been configured with a set of
trusted roots, either a well-known public set or a manually trusted roots, either a well-known public set or a manually
configured Certificate Authority (e.g., an organization's own configured Certificate Authority (e.g., an organization's own
Certificate Authority), normal certificate validation Certificate Authority), normal certificate validation
processing is appropriate. processing is appropriate.
skipping to change at page 19, line 18 skipping to change at page 20, line 31
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
NOT offer the STARTTLS extension to the initiating entity along NOT offer the STARTTLS extension to the initiating entity along
with the other stream features that are offered when the stream with the other stream features that are offered when the stream
is restarted. is restarted.
8. Whether the TLS negotiation results in success or failure, the 8. If the TLS negotiation results in success, the initiating entity
initiating entity SHOULD continue with SASL negotiation. SHOULD continue with SASL negotiation.
9. If the TLS negotiation results in failure, the receiving entity
MUST terminate both the stream and the underlying TCP connection.
5.2 Narrative 5.2 Narrative
When an initiating entity secures a stream with a receiving entity, When an initiating entity secures a stream with a receiving entity,
the steps involved are as follows: the steps involved are as follows:
1. Then initiating entity opens a TCP connection and initiates the 1. The initiating entity opens a TCP connection and initiates the
stream by sending the opening XML stream header to the receiving stream by sending the opening XML stream header to the receiving
entity, including the "version='1.0'" flag. entity, including the "version='1.0'" flag.
2. The receiving entity responds by opening a TCP connection and 2. The receiving entity responds by opening a TCP connection and
sending an XML stream header to the initiating entity. sending an XML stream header to the initiating entity.
3. The receiving entity offers the STARTTLS extension to the 3. The receiving entity offers the STARTTLS extension to the
initiating entity by sending it along with the list of supported initiating entity by sending it along with the list of supported
stream features. stream features.
4. Then initiating entity issues the STARTTLS command to instruct 4. The initiating entity issues the STARTTLS command to instruct the
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 an empty <proceed/> 5. The receiving entity MUST reply with either a <proceed/> element
element or an empty <failure/> element, but keep the underlying or a <failure/> element scoped by the
TCP connection open. 'urn:ietf:params:xml:ns:xmpp-tls' namespace, but keep the
underlying TCP connection open.
6. Then initiating entity begins a TLS negotiation in accordance 6. The initiating entity begins a TLS negotiation in accordance with
with RFC 2246 [16]. Upon completion of the negotiation, the RFC 2246 [13]. Upon completion of the negotiation, the
initiating entity initiates a new stream by sending a new opening initiating entity initiates a new stream by sending a new opening
XML stream header to the receiving entity. XML stream 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
skipping to change at page 20, line 26 skipping to change at page 22, line 4
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: authentication mechanisms and any other stream features (if TLS is
required for interaction with this server, the server SHOULD signal
that fact by including a <required/> element as a child of the
<starttls/> element):
<stream:features> <stream:features>
<starttls xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'>
<mechanisms xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <required/>
</starttls>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 4: Client sends the STARTTLS command to the server: Step 4: Client sends the STARTTLS command to the server:
<starttls xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5: Server informs client to proceed: Step 5: Server informs client to proceed:
<proceed xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5 (alt): Server informs client that TLS negotiation has failed Step 5 (alt): Server informs client that TLS negotiation has failed
(client SHOULD continue with stream authentication (Section 6)): and closes stream:
<failure xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 6: Client and server complete TLS negotiation via TCP. </stream:stream>
Step 6: Client and server complete TLS negotiation over the existing
TCP connection.
Step 7: Client initiates a new stream to the server: Step 7: Client initiates a new stream to the 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 8: Server responds by sending a stream header to the client Step 8: Server responds by sending a stream header to the client
along with any remaining negotiatiable stream features: along with any remaining negotiatiable stream features:
<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'>
<stream:features> <stream:features>
<mechanisms xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
<mechanism>EXTERNAL</mechanism> <mechanism>EXTERNAL</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 9: Client SHOULD continue with stream authentication (Section Step 9: Client SHOULD continue with stream authentication (Section
6). 6).
5.4 Server-to-Server Example 5.4 Server-to-Server Example
By bilateral agreement, server administrators SHOULD choose to use
TLS between two domains for the purpose of securing server-to-server
communications.
The following example shows the data flow for two servers securing a The following example shows the data flow for two servers securing a
stream using STARTTLS. stream using STARTTLS.
Step 1: Server1 initiates stream to Server2: Step 1: Server1 initiates stream to Server2:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
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:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
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: Server2 sends the STARTTLS extension to Server1 along with Step 3: Server2 sends the STARTTLS extension to Server1 along with
authentication mechanisms and any other stream features: authentication mechanisms and any other stream features (if TLS is
required for interaction with Server2, it SHOULD signal that fact by
including a <required/> element as a child of the <starttls/>
element):
<stream:features> <stream:features>
<starttls xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
<mechanisms xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <required/>
</starttls>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>KERBEROS_V4</mechanism> <mechanism>KERBEROS_V4</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 4: Server1 sends the STARTTLS command to Server2: Step 4: Server1 sends the STARTTLS command to Server2:
<starttls xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5: Server2 informs Server1 to proceed: Step 5: Server2 informs Server1 to proceed:
<proceed xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5 (alt): Server2 informs Server1 that TLS negotiation has failed Step 5 (alt): Server2 informs Server1 that TLS negotiation has failed
(Server1 SHOULD continue with stream authentication (Section 6)): and closes stream:
<failure xmlns='http://www.ietf.org/rfc/rfc2595.txt'/> <failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
</stream:stream>
Step 6: Server1 and Server2 complete TLS negotiation via TCP. Step 6: Server1 and Server2 complete TLS negotiation via TCP.
Step 7: Server1 initiates a new stream to Server2: Step 7: Server1 initiates a new 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 8: Server2 responds by sending a stream header to Server1 along Step 8: Server2 responds by sending a stream header to Server1 along
with any remaining negotiatiable stream features: with any remaining negotiatiable stream features:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>KERBEROS_V4</mechanism> <mechanism>KERBEROS_V4</mechanism>
<mechanism>EXTERNAL</mechanism> <mechanism>EXTERNAL</mechanism>
</mechanisms> </mechanisms>
</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. When one entity is already known to another (i.e., of XML streams. The secure and preferred method for authenticating
there is an existing trust relationship between the entities such as streams between two entities uses an XMPP adaptation of the Simple
that established when a user registers with a server or an Authentication and Security Layer (SASL) [14]. If SASL negotiation
administrator configures a server to trust another server), the is not possible, some level of trust MAY be established based on
preferred method for authenticating streams between the two entities
uses an XMPP adaptation of the Simple Authentication and Security
Layer (SASL) [21]. When there is no existing trust relationship
between two servers, some level of trust MAY be established based on
existing trust in DNS; the authentication method used in this case is existing trust in DNS; the authentication method used in this case is
the server dialback protocol that is native to XMPP (no such ad-hoc the server dialback protocol that is native to XMPP (no such ad-hoc
method is defined between a client and a server). If SASL is used for method is defined between a client and a server). If SASL is used
server-to-server authentication, the servers MUST NOT use dialback. for server-to-server authentication, the servers MUST NOT use
Both SASL authentication and dialback are described in this section. dialback. For further information about the relative merits of these
two 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 generalized method for adding authentication support to connection-
connection-based protocols. XMPP uses a generic XML namespace profile based protocols. XMPP uses a generic XML namespace profile for SASL
for SASL that conforms to section 4 ("Profiling Requirements") of RFC that conforms to section 4 ("Profiling Requirements") of RFC 2222
2222 [21] (the namespace identifier for this protocol is 'http:// [14] (the XMPP-specific namespace identifier is
www.iana.org/assignments/sasl-mechanisms'). 'urn:ietf:params:xml:ns:xmpp-sasl').
The following rules MUST be observed: 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 is NOT be negotiated using SASL). Conversely, if a security layer
to be negotiated via SASL, TLS MUST NOT be used. is to be negotiated via SASL, TLS MUST NOT be used.
2. If the initiating entity is capable of authenticating via SASL, 2. If the initiating entity is capable of authenticating via SASL,
it it MUST include the "version='1.0'" flag in the initiating it it MUST include the "version='1.0'" flag in the initiating
stream header. stream header.
3. If the receiving entity is capable of accepting authentications 3. If the receiving entity is capable of accepting authentications
via SASL, it MUST send one or more authentication mechanisms via SASL, it MUST send one or more authentication mechanisms
within a <mechanisms/> element in response to the opening stream within a <mechanisms/> element scoped by the
tag received from the initiating entity. 'urn:ietf:params:xml:ns:xmpp-sasl' namespace in response to the
opening stream tag received from the initiating entity.
4. If the SASL negotiation involves negotiation of a security layer, 4. If the SASL negotiation involves negotiation of a security layer,
the receiving entity MUST discard any knowledge obtained from the the receiving entity MUST discard any knowledge obtained from the
initiating entity which was not obtained from the SASL initiating entity which was not obtained from the SASL
negotiation itself. negotiation itself.
5. If the SASL negotiation involves negotiation of a security layer, 5. If the SASL negotiation involves negotiation of a security layer,
the initiating entity MUST discard any knowledge obtained from the initiating entity MUST discard any knowledge obtained from
the receiving entity which was not obtained from the SASL the receiving entity which was not obtained from the SASL
negotiation itself. negotiation itself.
The following syntax rules apply:
1. The initial challenge MUST include a realm, nonce, qop, charset,
and algorithm.
2. The inital response for client-to-server negotiation MUST include
a username, realm, nonce, cnonce, nc, qop, digest-uri, response,
charset, and authzid.
3. The inital response for server-to-server negotiation MUST include
a realm, nonce, cnonce, nc, qop, digest-uri, response, and
charset.
4. The realm-value MUST be no more than 1023 bytes in length and
MUST conform to the nameprep [8] profile of stringprep [9].
5. The username-value MUST be no more than 1023 bytes in length and
MUST conform to the nodeprep [10] profile of stringprep [9].
6. The response-value MUST be computed in accordance with the
relevant SASL mechanism as defined by the appropriate RFC (e.g.,
RFC 2831 [15] for digest authentication).
7. The resource identifier portion of the authzid-value MUST be no
more than 1023 bytes in length and MUST conform to the
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:
1. The initiating entity requests SASL authentication by including a 1. The initiating entity requests SASL authentication by including a
'version' attribute in the opening XML stream header sent to the 'version' attribute in the opening XML stream header sent to the
receiving entity, with the value set to "1.0". receiving entity, with the value set to "1.0".
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 that is sent as a child within a <mechanisms/> container element scoped by the
of the first-level <features/> element. If channel encryption 'urn:ietf:params:xml:ns:xmpp-sasl' namespace that is sent as a
must be established before a particular authentication mechanism child of a <features/> element in the streams namespace. If
may be used, the receiving entity MUST NOT provide that mechanism channel encryption must be established before a particular
in the list of available SASL authentication methods. If the authentication mechanism may be used, the receiving entity MUST
initiating entity presents a valid initiating entity certificate NOT provide that mechanism in the list of available SASL
during TLS negotiation, the receiving entity MAY offer the SASL authentication methods. If the initiating entity presents a
EXTERNAL mechanism to the initiating entity during stream valid initiating entity certificate during TLS negotiation, the
authentication (see RFC 2222 [21]). receiving entity MAY offer the SASL EXTERNAL mechanism to the
initiating entity during stream authentication (see RFC 2222
[14]).
3. The initiating entity selects a mechanism by sending an <auth/> 3. The initiating entity selects a mechanism by sending an <auth/>
element to the receiving entity; this element MAY optionally element scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl'
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 to the initiating entity by sending a <challenge/> element scoped by the
entity; this element MAY optionally contain character data. 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (which
MUST be computed in accordance with the SASL mechanism chosen by
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 to the receiving entity; this element MAY <response/> element scoped by the 'urn:ietf:params:xml:ns:xmpp-
optionally contain character data. sasl' namespace to the receiving entity; this element MAY
optionally contain character data (which MUST be computed in
accordance with the SASL mechanism chosen by 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 to the initiating entity. The particular a <failure/> element scoped by the 'urn:ietf:params:xml:ns:xmpp-
cause of failure optionally may be communicated in the 'code' sasl' namespace to the initiating entity. The particular cause
attribute of the <failure/> element, and may be 432 (password of failure SHOULD be communicated in an appropriate child element
transition is needed), 534 (authentication mechanism is too of the <failure/> element. The following conditions are defined:
weak), or 454 (temporary authentication failure).
* <authentication-mechanism-too-weak/>
* <invalid-realm/>
* <password-transition-required/>
* <resource-conflict/>
* <temporary-authentication-failure/>
* <user-not-authorized/>
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 to the initiating entity; this element MAY a <success/> element scoped by the 'urn:ietf:params:xml:ns:xmpp-
sasl' namespace to the initiating entity; this element MAY
optionally contain character data (in SASL terminology optionally contain character data (in SASL terminology
"additional data with success"). "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 [21] requires that the following Section 4 of the SASL specification [14] 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 possesed by an <auth/> element, optionally 'mechanism' attribute possessed by an <auth/> element, optionally
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. <abort/> element. (All of these elements are scoped by the
'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 effect headers are sent by both entities. The security layer takes
immediately following the ">" character of the empty <response/> effect immediately following the ">" character of the <response/>
element for the client and immediately following the closing ">" element for the client and immediately following the closing ">"
character of the <succeed/> element for the server. character of the <succeed/> element for the server. (Both of
these elements are scoped by the 'urn:ietf:params:xml:ns:xmpp-
sasl' namespace.)
use of the authorization identity: The authorization identity, if use of the authorization identity: The authorization identity is used
present, is unused by xmpp. by xmpp only in negotiation between a client and a server, and
denotes the "full JID" (user@host/resource) requested by the 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.
Step 1: Client initiates stream to server: Step 1: Client initiates stream to server:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
skipping to change at page 27, line 40 skipping to change at page 30, line 43
<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'>
Step 3: Server informs client of available authentication mechanisms: Step 3: Server informs client of available authentication mechanisms:
<stream:features> <stream:features>
<mechanisms xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 4: Client selects an authentication mechanism ("initial Step 4: Client selects an authentication mechanism:
response"):
<auth <auth
xmlns='http://www.iana.org/assignments/sasl-mechanisms' xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='DIGEST-MD5'/> mechanism='DIGEST-MD5'/>
Step 5: Server sends a base64-encoded challenge to the client: Step 5: Server sends a base64-encoded challenge to the client:
<challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi
xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\
qop="auth",charset=utf-8,algorithm=md5-sess qop="auth",charset=utf-8,algorithm=md5-sess
Step 6: Client responds to the challenge: Step 6: Client responds to the challenge:
<response xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
dXNlcm5hbWU9InJvYiIscmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik dXNlcm5hbWU9InJvYiIscmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik
9BNk1HOXRFUUdtMmhoIixcIGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5j 9BNk1HOXRFUUdtMmhoIixcIGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5j
PTAwMDAwMDAxLHFvcD1hdXRoLFwgZGlnZXN0LXVyaT0ieG1wcC9jYXRhY2 PTAwMDAwMDAxLHFvcD1hdXRoLFwgZGlnZXN0LXVyaT0ieG1wcC9jYXRhY2
x5c20uY3giLFwgcmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZ x5c20uY3giLFwgcmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZ
jIxNDNhZjcsY2hhcnNldD11dGYtOA== jIxNDNhZjcsY2hhcnNldD11dGYtOA==
</response> </response>
The decoded response is: The decoded response is:
username="rob",realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ username="rob",realm="cataclysm.cx",\
cnonce="OA6MHXh6VqTrRk",nc=00000001,qop=auth,\ digest-uri="xmpp/ nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\
cataclysm.cx",\ nc=00000001,qop=auth,digest-uri="xmpp/cataclysm.cx",\
response=d388dad90d4bbd760a152321f2143af7,charset=utf-8 response=d388dad90d4bbd760a152321f2143af7,charset=utf-8,\
authzid="rob@cataclysm.cx/myResource"
Step 7: Server sends another challenge to the client: Step 7: Server sends another challenge to the client:
<challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA== cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA==
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
rspauth=ea40f60335c427b5527b84dbabcdfffd rspauth=ea40f60335c427b5527b84dbabcdfffd
Step 8: Client responds to the challenge: Step 8: Client responds to the challenge:
<response xmlns='http://www.iana.org/assignments/sasl-mechanisms'/> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9: Server informs client of successful authentication: Step 9: Server informs client of successful authentication:
<success xmlns='http://www.iana.org/assignments/sasl-mechanisms'/> <success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9 (alt): Server informs client of failed authentication: Step 9 (alt): Server informs client of failed authentication:
<failure xmlns='http://www.iana.org/assignments/sasl-mechanisms' code='454'/> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<resource-conflict/>
</failure>
Step 10: Client initiates a new stream to the server: Step 10: Client initiates a new stream to the 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 11: Server responds by sending a stream header to the client, Step 11: Server responds by sending a stream header to the client,
skipping to change at page 29, line 37 skipping to change at page 32, line 39
<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
By bilateral agreement, server administrators MAY choose to use SASL
between two domains for the purpose of securing server-to-server
communications.
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.
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:
skipping to change at page 30, line 16 skipping to change at page 33, line 16
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
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: Server2 informs Server1 of available authentication Step 3: Server2 informs Server1 of available authentication
mechanisms: mechanisms:
<stream:features> <stream:features>
<mechanisms xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>KERBEROS_V4</mechanism> <mechanism>KERBEROS_V4</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 4: Server1 selects an authentication mechanism ("initial Step 4: Server1 selects an authentication mechanism:
response"):
<auth <auth
xmlns='http://www.iana.org/assignments/sasl-mechanisms' xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='DIGEST-MD5'/> mechanism='DIGEST-MD5'/>
Step 5: Server2 sends a base64-encoded challenge to Server1: Step 5: Server2 sends a base64-encoded challenge to Server1:
<challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi
xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\
qop="auth",charset=utf-8,algorithm=md5-sess qop="auth",charset=utf-8,algorithm=md5-sess
Step 6: Server1 responds to the challenge: Step 6: Server1 responds to the challenge:
<response xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixjbm9uY2U9Ik9B cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi
Nk1IWGg2VnFUclJrIixuYz0wMDAwMDAwMSxxb3A9YXV0aCxkaWdlc3QtdXJpPSJ4bXBwL2Nh xjbm9uY2U9Ik9BNk1IWGg2VnFUclJrIixuYz0wMDAwMDAwMSxxb3A9YXV0
dGFjbHlzbS5jeCIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcs aCxkaWdlc3QtdXJpPSJ4bXBwL2NhdGFjbHlzbS5jeCIscmVzcG9uc2U9ZD
Y2hhcnNldD11dGYtOAo= M4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcsY2hhcnNldD11dGYt
OAo=
</response> </response>
The decoded response is: The decoded response is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\
cnonce="OA6MHXh6VqTrRk",nc=00000001,qop=auth,\ digest-uri="xmpp/ nc=00000001,qop=auth,digest-uri="xmpp/cataclysm.cx",\
cataclysm.cx",\
response=d388dad90d4bbd760a152321f2143af7,charset=utf-8 response=d388dad90d4bbd760a152321f2143af7,charset=utf-8
Step 7: Server2 sends another challenge to Server1: Step 7: Server2 sends another challenge to Server1:
<challenge xmlns='http://www.iana.org/assignments/sasl-mechanisms'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA== cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA==
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
rspauth=ea40f60335c427b5527b84dbabcdfffd rspauth=ea40f60335c427b5527b84dbabcdfffd
Step 8: Server1 responds to the challenge: Step 8: Server1 responds to the challenge:
<response xmlns='http://www.iana.org/assignments/sasl-mechanisms'/> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9: Server2 informs Server1 of successful authentication: Step 9: Server2 informs Server1 of successful authentication:
<success xmlns='http://www.iana.org/assignments/sasl-mechanisms'/> <success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9 (alt): Server2 informs Server1 of failed authentication: Step 9 (alt): Server2 informs Server1 of failed authentication:
<failure xmlns='http://www.iana.org/assignments/sasl-mechanisms' code='454'/> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<temporary-auth-failure/>
</failure>
Step 10: Server1 initiates a new stream to Server2: Step 10: Server1 initiates a new 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 11: Server2 responds by sending a stream header to Server1, with Step 11: Server2 responds by sending a stream header to Server1, with
the stream already authenticated (not followed by further stream the stream already authenticated (not followed by further stream
skipping to change at page 32, line 4 skipping to change at page 35, line 8
<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'>
6.2 Dialback Authentication 6.2 Dialback Authentication
XMPP includes a protocol-level method for verifying that a connection XMPP includes a protocol-level method for verifying that a connection
between two servers can be trusted (at least as much as the DNS can between two servers can be trusted as much as the DNS can be trusted.
be trusted). The method is called dialback and is used only within The method is called dialback and is used only within XML streams
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 not intended as a mechanism for securing or encrypting Dialback is decidedly not intended as a mechanism for securing or
the streams between servers as is done via SASL and TLS, only for encrypting the streams between servers as is done via SASL and TLS,
helping to prevent the spoofing of a server and the sending of false only for helping to prevent the spoofing of a server and the sending
data from it. Domains requiring more robust security SHOULD use TLS of false data from it. In particular, dialback authentication is
or SASL as defined above. susceptible to DNS poisoning attacks unless DNSSec [29] is used.
Furthermore, even if the DNS information is accurate, dialback
authentication cannot protect from attacks where the attacker is
capable of hijacking the IP address of the remote domain. Domains
requiring more robust security SHOULD use TLS and SASL as defined
above.
Server dialback is made possible by the existence of DNS, since one Server dialback is made possible by the existence of DNS, since one
server can verify that another server which is connecting to it is server can verify that another server which is connecting to it is
authorized to represent a given server on the Jabber network. All DNS authorized to represent a given hostname. All DNS hostname
hostname resolutions MUST first resolve the hostname using an SRV resolutions MUST first resolve the hostname using an SRV [17] record
[23] record of _jabber._tcp.server. If the SRV lookup fails, the of _jabber._tcp.server. If the SRV lookup fails, the fallback is a
fallback is a normal A lookup to determine the IP address, using the normal A lookup to determine the IP address, using the jabber-server
jabber-server port of 5269 assigned by the Internet Assigned Numbers port of 5269 assigned by the Internet Assigned Numbers Authority [5].
Authority [6].
Note: the method for generating and verifying the keys used in the The method for generating and verifying the keys used in the dialback
dialback protocol MUST take into account the hostnames being used, protocol MUST take into account the hostnames being used, the random
along with a secret known only by the receiving server and the random ID generated for the stream, and a secret known by the authoritative
ID generated for the stream. Generating unique but verifiable keys is server's network. Generating unique but verifiable keys is important
important to prevent common man-in-the-middle attacks and server to prevent common man-in-the-middle attacks and server spoofing.
spoofing.
In the description that follows we use the following terminology: Any error that occurs during dialback negotiation MUST be considered
a stream error, resulting in termination of the stream and of the
underlying TCP connection. The possible error conditions are
specified in the protocol description below.
The following terminology applies:
o Originating Server -- the server that is attempting to establish a o Originating Server -- the server that is attempting to establish a
connection between the two servers connection between two domains.
o Receiving Server -- the server that is trying to authenticate that o Receiving Server -- the server that is trying to authenticate that
Originating Server represents the Jabber server which it claims to Originating Server represents the domain which it claims to be.
be
o Authoritative Server -- the server that is given when a DNS lookup o Authoritative Server -- the server that answers to the DNS
is performed on the name that Originating Server initially gave; hostname asserted by Originating Server; for basic environments
for basic environments this will be Originating Server, but it this will be Originating Server, but it could be a separate
could be a separate machine in Originating Server's network machine in Originating Server's network.
The following is a brief summary of the order of events in dialback: The following is a brief summary of the order of events in dialback:
1. Originating Server establishes a connection to Receiving Server. 1. Originating Server establishes a connection to Receiving Server.
2. Originating Server sends a 'key' value over the connection to 2. Originating Server sends a 'key' value over the connection to
Receiving Server. Receiving Server.
3. Receiving Server establishes a connection to Authoritative 3. Receiving Server establishes a connection to Authoritative
Server. Server.
skipping to change at page 34, line 12 skipping to change at page 37, line 23
| | | |
| validate dialback key | | validate dialback key |
| <---------------------- | | <---------------------- |
| |
| report dialback result | | report dialback result |
| <---------------------- | | <---------------------- |
| | | |
6.2.1 Dialback Protocol 6.2.1 Dialback Protocol
The traffic sent between the servers is as follows: The interaction between the servers is as follows:
1. Originating Server establishes TCP connection to Receiving 1. Originating Server establishes TCP connection to Receiving
Server Server.
2. Originating Server sends a stream header to Receiving Server 2. Originating Server sends a stream header to Receiving Server:
(the 'to' and 'from' attributes are NOT REQUIRED on the root
stream element):
<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 value of the xmlns:db namespace declaration indicates Note: the 'to' and 'from' attributes are NOT REQUIRED on the
to Receiving Server that Originating Server supports dialback. root stream element. The inclusion of the xmlns:db namespace
declaration with the name shown indicates to Receiving Server
that Originating Server supports dialback. If the namespace
name is incorrect, then Receiving Server MUST generate an
<invalid-namespace/> stream error condition and terminate both
the stream and the underlying TCP connection.
3. Receiving Server sends a stream header back to Originating 3. Receiving Server SHOULD send a stream header back to Originating
Server (the 'to' and 'from' attributes are NOT REQUIRED on the Server, including a unique ID for this interaction:
root stream element):
<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'
id='457F9224A0...'> id='457F9224A0...'>
Note: Receiving Server is NOT REQUIRED to reply, and SHOULD NOT
reply if there exists an established session between Receiving
Server and the hostname asserted by Originating Server. The
'to' and 'from' attributes are NOT REQUIRED on the root stream
element. If the namespace name is incorrect, then Originating
Server MUST generate an <invalid-namespace/> stream error
condition and terminate both the stream and the underlying TCP
connection.
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. Server between sessions. The key generated by Originating
Server 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
shared by Originating Server and Authoritative Server. If the
value of the 'to' address does not match a hostname recognized
by Receiving Server, then Receiving Server MUST generate a
<host-unknown/> stream error condition and terminate both the
stream and the underlying TCP connection. If the value of the
'from' address does not match the hostname represented by
Originating Server when opening the TCP connection (or any
validated domain), then Receiving Server MUST generate a
<nonmatching-hosts/> stream error condition and terminate both
the stream and the underlying TCP connection.
5. Receiving Server now establishes a connection back to 5. Receiving Server establishes a TCP connection back to the domain
Originating Server, getting Authoritative Server. name asserted by Originating Server, as a result of which it
connects to Authoritative Server. (Note: as an optimization, an
implementation MAY reuse an existing trusted connection here
rather than opening a new TCP connection.)
6. Receiving Server sends Authoritative Server a stream header (the 6. Receiving Server sends Authoritative Server a stream header:
'to' and 'from' attributes are NOT REQUIRED on the root stream
element):
<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
root stream element. If the namespace name is incorrect, then
Authoritative Server MUST generate an <invalid-namespace/>
stream error condition and terminate both the stream and the
underlying TCP connection.
7. Authoritative Server sends Receiving Server a stream header: 7. Authoritative Server sends Receiving Server a stream header:
<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'
id='1251A342B...'> id='1251A342B...'>
8. Receiving Server sends Authoritative Server a stanza indicating Note: if the namespace name is incorrect, then Receiving Server
it wants Authoritative Server to verify a key: MUST generate an <invalid-namespace/> stream error condition and
terminate both the stream and the underlying TCP connection
between it and Authoritative Server. If the ID does not match
that provided by Receiving Server in Step 3, then Receiving
Server MUST generate an <invalid-id/> stream error condition and
terminate both the stream and the underlying TCP connection
between it and Authoritative Server. If either of the foregoing
stream errors occurs between Receiving Server and Authoritative
Server, then Receiving Server MUST generate a <remote-
connection-failed/> stream error condition and terminate both
the stream and the underlying TCP connection between it and
Originating Server.
8. Receiving Server sends Authoritative Server a stanza requesting
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>
Note: passed here are the hostnames, the original identifier Note: passed here are the hostnames, the original identifier
from Receiving Server's stream header to Originating Server in from Receiving Server's stream header to Originating Server in
step 2, and the key Originating Server gave Receiving Server in Step 3, and the key that Originating Server sent to Receiving
step 3. Based on this information and shared secret information Server in Step 4. Based on this information and shared secret
within the 'Originating Server' network, the key is verified. information within the Authoritative Server's network, the key
Any verifiable method can be used to generate the key. is verified. Any verifiable method MAY be used to generate the
key. If the value of the 'to' address does not match a hostname
recognized by Authoritative Server, then Authoritative Server
MUST generate a <host-unknown/> stream error condition and
terminate both the stream and the underlying TCP connection. If
the value of the 'from' address does not match the hostname
represented by Receiving Server when opening the TCP connection
(or any validated domain), then Authoritative Server MUST
generate a <nonmatching-hosts/> stream error condition and
terminate both the stream and the underlying TCP connection.
9. Authoritative Server sends a stanza back to Receiving Server 9. Authoritative Server sends a stanza back to Receiving Server
verifying whether the key was valid or invalid: verifying whether the key was valid or invalid:
<db:verify <db:verify
from='Originating Server' from='Originating Server'
to='Receiving Server' to='Receiving Server'
type='valid' type='valid'
id='457F9224A0...'/> id='457F9224A0...'/>
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9. Authoritative Server sends a stanza back to Receiving Server 9. Authoritative Server sends a stanza back to Receiving Server
verifying whether the key was valid or invalid: verifying whether the key was valid or invalid:
<db:verify <db:verify
from='Originating Server' from='Originating Server'
to='Receiving Server' to='Receiving Server'
type='valid' type='valid'
id='457F9224A0...'/> id='457F9224A0...'/>
or or
<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
in Step 3, then Receiving Server MUST generate an <invalid-id/>
stream error condition and terminate both the stream and the
underlying TCP connection. If the value of the 'to' address
does not match a hostname recognized by Receiving Server, then
Receiving Server MUST generate a <host-unknown/> stream error
condition and terminate both the stream and the underlying TCP
connection. If the value of the 'from' address does not match
the hostname represented by Originating Server when opening the
TCP connection (or any validated domain), then Receiving Server
MUST generate a <nonmatching-hosts/> stream error condition and
terminate both the stream and the underlying TCP connection.
10. Receiving Server informs Originating Server of the result: 10. Receiving Server informs Originating Server of the result:
<db:result <db:result
from='Receiving Server' from='Receiving Server'
to='Originating Server' to='Originating Server'
type='valid'/> type='valid'/>
Note: At this point the connection has either been validated via Note: At this point the connection has either been validated via
a type='valid', or reported as invalid. Once the connection is a type='valid', or reported as invalid. If the connection is
invalid, then Receiving Server MUST terminate both the stream
and the underlying TCP connection. If the connection is
validated, data can be sent by Originating Server and read by validated, data can be sent by Originating Server and read by
Receiving Server; before that, all data stanzas sent to Receiving Server; before that, all data stanzas sent to
Receiving Server SHOULD be dropped. As a final guard against Receiving Server SHOULD be silently dropped.
domain spoofing, Receiving Server MUST verify that all XML
stanzas received from Originating Server include a 'from' Even if dialback negotiation is successful, a server MUST verify that
attribute and that the value of that attribute includes the all XML stanzas received from the other server include a 'from'
validated domain. In addition, all XML stanzas MUST include a attribute and a 'to' attribute; if a stanza does not meet this
'to' attribute. restriction, the server that receives the stanza MUST generate an
<invalid-xml/> stream error condition and terminate both the stream
and the underlying TCP connection. Furthermore, a server MUST verify
that the 'from' attribute of stanzas received from the other server
includes the validated domain (or any validated domain); if a stanza
does not meet this restriction, the server that receives the stanza
MUST generate a <nonmatching-hosts/> stream error condition and
terminate both the stream and the underlying TCP connection. Both of
these checks help to prevent spoofing related to particular stanzas.
7. XML Stanzas 7. XML Stanzas
7.1 Overview 7.1 Overview
Once the XML streams in each direction have been authenticated and Once the XML streams in each direction have been authenticated and
(if desired) encrypted, XML stanzas can be sent over the streams. (if desired) encrypted, XML stanzas can be sent over the streams.
Three XML stanza types are defined for the 'jabber:client' and Three XML stanza types are defined for the 'jabber:client' and
'jabber:server' namespaces: <message/>, <presence/>, and <iq/>. 'jabber:server' namespaces: <message/>, <presence/>, and <iq/>.
In essence, the <message/> stanza type can be seen as a "push" In essence, the <message/> stanza type can be seen as a "push"
mechanism whereby one entity pushes information to another entity, mechanism whereby one entity pushes information to another entity,
similar to the communications that occur in a system such as email. similar to the communications that occur in a system such as email.
The <presence/> element can be seen as a basic broadcast or The <presence/> element can be seen as a basic broadcast or "publish-
"publish-subscribe" mechanism, whereby multiple entities receive subscribe" mechanism, whereby multiple entities receive information
information (in this case, presence information) about an entity to (in this case, presence information) about an entity to which they
which they have subscribed. The <iq/> element can be seen as a have subscribed. The <iq/> element can be seen as a "request-
"request-response" mechanism similar to HTTP, whereby two entities response" mechanism similar to HTTP, whereby two entities can engage
can engage in a structured conversation using 'get' or 'set' requests in a structured conversation using 'get' or 'set' requests and
and 'result' or 'error' responses. 'result' or 'error' responses.
The syntax for these stanza types is defined below. The syntax for these stanza types is defined below.
7.2 Common Attributes 7.2 Common Attributes
Five attributes are common to message, presence, and IQ stanzas. Five attributes are common to message, presence, and IQ stanzas.
These are defined below. These are defined below.
7.2.1 to 7.2.1 to
The 'to' attribute specifies the JID of the intended recipient for The 'to' attribute specifies the JID of the intended recipient for
the stanza. In the 'jabber:client' namespace, a stanza SHOULD possess the stanza.
a 'to' attribute, although a stanza sent from a client to a server
for handling by that server (e.g., presence sent to the server for In the 'jabber:client' namespace, a stanza SHOULD possess a 'to'
attribute, although a stanza sent from a client to a 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. In the 'jabber:server' namespace, a stanza MUST possess a attribute.
'to' attribute.
In the 'jabber:server' namespace, a stanza MUST possess a 'to'
attribute; if a server receives a stanza that does not meet this
restriction, it MUST generate an <invalid-xml/> stream error
condition and terminate both the stream and the underlying TCP
connection.
7.2.2 from 7.2.2 from
The 'from' attribute specifies the JID of the sender. The 'from' attribute specifies the JID of the sender.
In the 'jabber:client' namespace, a client MUST NOT include a 'from' In the 'jabber:client' namespace, a client MUST NOT include a 'from'
attribute on the stanzas it sends to a server; if a server receives a attribute on the stanzas it sends to a server; if a server receives a
stanza from a client and the stanza possesses a 'from' attribute, it stanza from a client and the stanza possesses a 'from' attribute, it
MUST ignore the value of the 'from' attribute and MAY return an error MUST ignore the value of the 'from' attribute and MAY return an error
to the sender. In addition, a server MUST stamp stanzas received from to the sender. In addition, a server MUST stamp stanzas received
a client with the user@domain/resource (full JID) of the connected from a client with the user@domain/resource (full JID) of the
resource that generated the stanza. connected resource that generated the stanza.
In the 'jabber:server' namespace, a stanza MUST possess a 'from' In the 'jabber:server' namespace, a stanza MUST possess a 'from'
attribute. In particular, a server MUST include a 'from' attribute on attribute; if a server receives a stanza that does not meet this
stanzas it routes to other servers. The domain identifier of the JID restriction, it MUST generate an <invalid-xml/> stream error
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
server (or a subdomain thereof) as communicated in the SASL sending server (or any validated domain) as communicated in the SASL
negotiation or dialback negotiation. negotiation or dialback negotiation; if a server receives a stanza
that does not meet this restriction, it MUST generate a <nonmatching-
hosts/> stream error condition. Both of these conditions MUST result
in closing of the stream and termination of the 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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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
specifying the default language of any CDATA sections of the stanza specifying the default language of any CDATA sections of the stanza
or its child elements. An IQ stanza SHOULD NOT possess an 'xml:lang' or its child elements. An IQ stanza SHOULD NOT possess an 'xml:lang'
attribute, since it is merely a vessel for data in other namespaces attribute, since it is merely a vessel for data in other namespaces
and does not itself contain children that have CDATA. The value of and does not itself contain children that have CDATA. The value of
the 'xml:lang' attribute MUST be an NMTOKEN and MUST conform to the the 'xml:lang' attribute MUST be an NMTOKEN and MUST conform to the
format defined in RFC 3066 [22]. format defined in RFC 3066 [16].
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 a specifies the conversational context of the message. The sending of
message stanza without a 'type' attribute signals that the message a message stanza without a 'type' attribute signals that the message
stanza is a single message. However, the 'type' attribute MAY also stanza is a single message. However, the 'type' attribute MAY also
have one of the following values: have one of the following values:
o chat o chat
o error o error
o groupchat o groupchat
o headline o headline
For information about the meaning of these message types, refer to For information about the meaning of these message types, refer to
XMPP IM [2]. XMPP IM [22].
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", and as long as the element name "http://etherx.jabber.org/streams".
does not match that of one of the core data elements, stream
elements, or defined children thereof.
In accordance with the default namespace declaration, by default a In accordance with the default namespace declaration, by default a
message stanza is in the 'jabber:client' or 'jabber:server' message stanza is in the 'jabber:client' or 'jabber:server'
namespace, which defines certain allowable children of message namespace, which defines certain allowable children of message
stanzas. If the message stanza is of type "error", it MUST include an stanzas. If the message stanza is of type "error", it MUST include
<error/> child; for details, see Section 7.7. If the message stanza an <error/> child; for details, see Section 7.7. If the message
has no 'type' attribute or has a 'type' attribute with a value of stanza has no 'type' attribute or has a 'type' attribute with a value
"chat", "groupchat", or "headline", it MAY contain any of the of "chat", "groupchat", or "headline", it MAY contain any of the
following child elements without an explicit namespace declaration: following child elements without an explicit namespace declaration:
7.3.2.1 Body 7.3.2.1 Body
The <body/> element contains the textual contents of the message; The <body/> element contains the textual contents of the message;
normally included but NOT REQUIRED. The <body/> element MUST NOT normally included but NOT REQUIRED. The <body/> element 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 MUST 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. The possesses an 'xml:lang' attribute with a distinct language value.
<subject> element MUST NOT contain mixed content. The <subject> element MUST NOT contain mixed content.
7.3.2.3 Thread 7.3.2.3 Thread
The <thread/> element contains a random string that is generated by The <thread/> element contains a random string that is generated by
the sender and that SHOULD be copied back in replies; it is used for the sender and that SHOULD be copied back in replies; it is used for
tracking a conversation thread (sometimes referred to as an "IM tracking a conversation thread (sometimes referred to as an "IM
session") between two entities. If used, it MUST be unique to that session") between two entities. If used, it MUST be unique to that
conversation thread within the stream and MUST be consistent conversation thread within the stream and MUST be consistent
throughout that conversation. The use of the <thread/> element is throughout that conversation. The use of the <thread/> element is
optional and is not used to identify individual messages, only optional and is not used to identify individual messages, only
conversations. Only one <thread/> element MAY be included in a conversations. Only one <thread/> element MAY be included in a
message stanza, and it MUST NOT possess any attributes. The <thread/> message stanza, and it MUST NOT possess any attributes. The <thread/
element MUST be treated as an opaque string by entities; no semantic > element MUST be treated as an opaque string by entities; no
meaning may be derived from it, and only exact, case-insensitve semantic meaning may be derived from it, and only exact, case-
comparisons be made against it. The <thread> element MUST NOT contain insensitve comparisons be made against it. The <thread> element MUST
mixed content. NOT contain mixed content.
The method for generating thread IDs SHOULD be as follows: The method for generating thread IDs SHOULD be as follows:
1. concatenate the sender's full JID (user@host/resource) with the 1. concatenate the sender's full JID (user@host/resource) with the
recipient's full JID recipient's full JID
2. concatenate these JID strings with a full ISO-8601 timestamp 2. concatenate these JID strings with a full ISO-8601 timestamp
including year, month, day, hours, minutes, seconds, and UTC including year, month, day, hours, minutes, seconds, and UTC
offset in the following format: yyyy-mm-dd-Thh:mm:ss-hh:mm offset in the following format: yyyy-mm-dd-Thh:mm:ss-hh:mm
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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 [2]. found in XMPP IM [22].
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", and as long as the element name "http://etherx.jabber.org/streams".
does not match that of one of the core data elements, stream
elements, or defined children thereof.
In accordance with the default namespace declaration, by default a In accordance with the default namespace declaration, by default a
presence stanza is in the 'jabber:client' or 'jabber:server' presence stanza is in the 'jabber:client' or 'jabber:server'
namespace, which defines certain allowable children of presence namespace, which defines certain allowable children of presence
stanzas. If the presence stanza is of type "error", it MUST include stanzas. If the presence stanza is of type "error", it MUST include
an <error/> child; for details, see Section 7.7. If the presence an <error/> child; for details, see Section 7.7. If the presence
stanza possesses no 'type' attribute, it MAY contain any of the stanza possesses no 'type' attribute, it MAY contain any of the
following child elements (note that the <status/> child MAY be sent following child elements (note that the <status/> child MAY be sent
in a presence stanza of type "unavailable" or, for historical in a presence stanza of type "unavailable" or, for historical
reasons, "subscribe"): reasons, "subscribe"):
7.4.2.1 Show 7.4.2.1 Show
The <show/> element specifies describes the availability status of an The optional <show/> element specifies a particular availability
entity or specific resource. Only one <show/> element MAY be included status of an entity or specific resource (if a <show/> element is not
in a presence stanza, and it MUST NOT possess any attributes. The provided, default availability is assumed (if a <show/> element is
value SHOULD be one of the following (values other than these four not provided, default availability is assumed)). Only one <show/>
MAY be ignored; additional availability types could be defined element MAY be included in a presence stanza, and it SHOULD NOT
through a properly-namespaced child element of the presence stanza): possess any attributes. The CDATA value SHOULD be one of the
following (values other than these four SHOULD be ignored; additional
availability types could be defined through a properly-namespaced
child element of the presence stanza):
o away o away
o chat o chat
o xa o xa
o dnd o dnd
For information about the meaning of these values, refer to XMPP IM For information about the meaning of these values, refer to XMPP IM
[2]. [22].
7.4.2.2 Status 7.4.2.2 Status
The optional <status/> element specifies 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 MUST 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 MAY 'xml:lang' attribute. Multiple instances of the <status/> element
be included but only if each instance possesses an 'xml:lang' MAY be included but only if each instance possesses an 'xml:lang'
attribute with a distinct language value. attribute with a distinct language value.
7.4.2.3 Priority 7.4.2.3 Priority
The optional <priority/> element specifies the priority level of the The optional <priority/> element specifies the priority level of the
connected resource. The value may be any integer between -128 to 127. connected resource. The value may be any integer between -128 to
Only one <priority/> element MAY be included in a presence stanza, 127. Only one <priority/> element MAY be included in a presence
and it MUST NOT possess any attributes. For information regarding the stanza, and it MUST NOT possess any attributes. For information
use of priority values in stanza routing within IM applications, see regarding the use of priority values in stanza routing within IM
XMPP IM [2]. applications, see XMPP IM [22].
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 [24]. IQ stanzas in the 'jabber:client' or ways to HTTP [30]. 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):
skipping to change at page 43, line 51 skipping to change at page 49, line 13
stanza by sending a further IQ response of type 'result' or 'error'; stanza by sending a further IQ response of type 'result' or 'error';
however, as shown above, the requesting entity MAY send another however, as shown above, the requesting entity MAY send another
request (e.g., an IQ of type 'set' in order to provide required request (e.g., an IQ of type 'set' in order to provide required
information discovered through a get/result pair). information discovered through a get/result pair).
7.5.2 Types of IQ 7.5.2 Types of IQ
The 'type' attribute of an IQ stanza is REQUIRED. The 'type' The 'type' attribute of an IQ stanza is REQUIRED. The 'type'
attribute specifies a distinct step within a request-response attribute specifies a distinct step within a request-response
interaction. The value SHOULD be one of the following (all other interaction. The value SHOULD be one of the following (all other
values MAY be ignored): values SHOULD be ignored):
o get -- The stanza is a request for information. o get -- The stanza is a request for information.
o set -- The stanza provides required data, sets new values, or o set -- The stanza provides required data, sets new values, or
replaces existing values. replaces existing values.
o result -- The stanza is a response to a successful get or set o result -- The stanza is a response to a successful get or set
request. request.
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 get or set. a previously-sent get or set.
7.5.3 Children 7.5.3 Children
As described under extended namespaces (Section 7.6), an IQ stanza As described under extended namespaces (Section 7.6), an IQ stanza
MAY contain any properly-namespaced child element as long as the MAY contain any properly-namespaced child element as long as the
namespace name is not "jabber:client", "jabber"server", or "http:// namespace name is not "jabber:client", "jabber"server", or "http://
etherx.jabber.org/streams", and as long as the element name does not etherx.jabber.org/streams". However, an IQ stanza contains no
match that of one of the core data elements, stream elements, or children in the 'jabber:client' or 'jabber:server' namespace since it
defined children thereof. However, an IQ stanza contains no children is a vessel for XML in another namespace.
in the 'jabber:client' or 'jabber:server' namespace since it is a
vessel for XML in another namespace.
If the IQ stanza is of type "error", it MUST include an <error/> If the IQ stanza is of type "error", it MUST include an <error/>
child; for details, see Section 7.7. child; for details, see Section 7.7.
7.6 Extended Namespaces 7.6 Extended Namespaces
While the core data elements in the "jabber:client" or While the core data elements in the "jabber:client" or
"jabber:server" namespace (along with their attributes and child "jabber:server" namespace (along with their attributes and child
elements) provide a basic level of functionality for messaging and elements) provide a basic level of functionality for messaging and
presence, XMPP uses XML namespaces to extend the core data elements presence, XMPP uses XML namespaces to extend the core data elements
for the purpose of providing additional functionality. Thus a for the purpose of providing additional functionality. Thus a
message, presence, or IQ stanza MAY house one or more optional child message, presence, or IQ stanza MAY house one or more optional child
elements containing content that extends the meaning of the message elements containing content that extends the meaning of the message
(e.g., an encrypted form of the message body). This child element MAY (e.g., an encrypted form of the message body). This child element
be any element (other than the core data elements, stream elements, MAY be have any name and MUST possess an 'xmlns' namespace
or defined children thereof). The child element MUST possess an declaration (other than "jabber:client", "jabber:server", or "http://
'xmlns' namespace declaration (other than the stream namespace and etherx.jabber.org/streams") that defines all data contained within
the default namespace) that defines all data contained within the the child element.
child element.
Support for any given extended namespace is OPTIONAL on the part of Support for any given extended namespace is OPTIONAL on the part of
any implementation. If an entity does not understand such a any implementation. If an entity does not understand such a
namespace, it MUST ignore the associated XML data (if the stanza is namespace, the entity's expected behavior depends on whether the
being routed on to another entity, ignore means "pass it on entity is (1) the recipient or (2) an entity that is routing the
untouched"). If an entity receives a message or presence stanza that stanza to the recipient. In particular:
contains XML data in an extended namespace it does not understand,
the portion of the stanza that is in the unknown namespace SHOULD be Recipient: If a recipient receives a stanza that contains a child
ignored. If an entity receives a message stanza without a <body/> element it does not understand, it SHOULD ignore that specific XML
element but containing only a child element bound by a namespace it data, i.e., it SHOULD not process it or present it to a user or
does not understand, it MUST ignore the entire stanza. If an entity associated application (if any). In particular:
receives an IQ stanza in a namespace it does not understand, the
entity SHOULD return an IQ stanza of type "error" with an error * If an entity receives a message or presence stanza that
condition of <feature-not-implemented/>. contains XML data in an extended namespace it does not
understand, the portion of the stanza that is in the unknown
namespace SHOULD be ignored.
* If an entity receives a message stanza without a <body/>
element but containing only a child element bound by a
namespace it does not understand, it MUST ignore the entire
stanza/
* If an entity receives an IQ stanza in a namespace it does not
understand, the entity SHOULD return an IQ stanza of type
"error" with an error condition of <feature-not-implemented/>.
Router: If a routing entity (usually a server) handles a stanza that
contains a child element it does not understand, it SHOULD ignore
the associated XML data by passing it on untouched to the
recipient.
7.7 Stanza Errors 7.7 Stanza Errors
As defined below, stanza-related errors are handled in a manner As defined below, 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:
skipping to change at page 45, line 48 skipping to change at page 51, line 25
<stanza-name to='sender' type='error'> <stanza-name to='sender' type='error'>
[include sender XML here] [include sender XML here]
<error class='error-class'> <error class='error-class'>
<stanza-condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'> <stanza-condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
<descriptive-element-name/> <descriptive-element-name/>
</stanza-condition> </stanza-condition>
</error> </error>
</stanza-name> </stanza-name>
The stanza name is one of message, presence, or iq. The stanza-name is one of message, presence, or iq.
The value of the 'class' attribute must be one of the following: The value of the 'class' attribute MUST be one of the following:
o access -- the condition relates to access rights, permissions, or o access -- the condition relates to access rights, permissions, or
authorization authorization
o address -- the condition relates to the JID or domain to which the o address -- the condition relates to the JID or domain to which the
stanza was addressed stanza was addressed
o app -- the condition is particular to an application and is o app -- the condition is particular to an application and is
specified in a namespace other than specified in a namespace other than 'urn:ietf:params:xml:ns:xmpp-
'urn:ietf:params:xml:ns:xmpp-stanzas' stanzas'
o format -- the condition relates to XML format or structure o format -- the condition relates to XML format or structure
o recipient -- the condition relates to the state or capabilities of o recipient -- the condition relates to the state or capabilities of
the recipient (which may be the server) the recipient (which may be the server)
o server -- the condition relates to the internal state of the o server -- the condition relates to the internal state of the
server server
The <stanza-condition/> element MUST contain a child element that The <stanza-condition/> element MUST contain a child element that
specifies a particular stanza-related error condition, as defined in specifies a particular stanza-related error condition, as defined in
the next section. (Note: the XML namespace name the next section. (Note: the XML namespace name
'urn:ietf:params:xml:ns:xmpp-stanzas' that scopes the 'urn:ietf:params:xml:ns:xmpp-stanzas' that scopes the <stanza-
<stanza-condition/> element adheres to the format defined in The IETF condition/> element adheres to the format defined in The IETF XML
XML Registry [15].) Registry [24].)
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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as part or all of the JID of the intended recipient could not be as part or all of the JID of the intended recipient could not be
contacted within a reasonable amount of time; the associated class contacted within a reasonable amount of time; the associated class
is "server". is "server".
o <service-unavailable/> -- the service requested is currently o <service-unavailable/> -- the service requested is currently
unavailable on the server; the associated class is "server". unavailable on the server; the associated class is "server".
7.7.4 Extensibility 7.7.4 Extensibility
If desired, an XMPP application MAY provide custom error information; If desired, an XMPP application MAY provide custom error information;
this MUST be contained in a properly-namespaced child of the the error class MUST be "app" and the data MUST be contained in a
<stanza-condition/> element (i.e., the namespace name MUST NOT be one properly-namespaced child of the <stanza-condition/> element (i.e.,
of namespace names defined herein). the namespace name MUST NOT be one of namespace names defined
herein).
8. XML Usage within XMPP 8. XML Usage within XMPP
8.1 Restrictions 8.1 Restrictions
XMPP is a simplified and specialized protocol for streaming XML XMPP is a simplified and specialized protocol for streaming XML
elements in order to exchange messages and presence information in elements in order to exchange messages and presence information in
close to real time. Because XMPP does not require the parsing of close to real time. Because XMPP does not require the parsing of
arbitrary and complete XML documents, there is no requirement that arbitrary and complete XML documents, there is no requirement that
XMPP must support the full XML specification [1]. In particular, the XMPP must support the full XML specification [1]. In particular, the
skipping to change at page 48, line 33 skipping to change at page 54, line 33
o internal or external DTD subsets (Section 2.8) o internal or external DTD subsets (Section 2.8)
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 [14] 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 namespaces strict boundaries of data ownership. The basic function of
is to separate different vocabularies of XML elements that are namespaces is to separate different vocabularies of XML elements that
structurally mixed together. Ensuring that XMPP-compliant XML is are structurally mixed together. Ensuring that XMPP-compliant XML is
namespace-aware enables any XML to be structurally mixed with any namespace-aware enables any XML to be structurally mixed with any
data element within XMPP. data element within XMPP.
Additionally, XMPP is more strict about namespace prefixes than the Additionally, XMPP is more strict about namespace prefixes than the
XML namespace specification requires. XML namespace specification requires.
8.3 Validation 8.3 Validation
A server is not responsible for validating the XML elements forwarded Except as noted with regard to 'to' and 'from' addresses for stanzas
to a client or another server; an implementation MAY choose to within the 'jabber:server' namespace, a server is not responsible for
provide only validated data elements but is NOT REQUIRED to do so. validating the XML elements forwarded to a client or another server;
Clients SHOULD NOT rely on the ability to send data which does not an implementation MAY choose to provide only validated data elements
conform to the schemas, and SHOULD ignore any non-conformant elements but is NOT REQUIRED to do so. Clients SHOULD NOT rely on the ability
or attributes on the incoming XML stream. Validation of XML streams to send data which does not conform to the schemas, and SHOULD ignore
and stanzas is NOT REQUIRED or recommended, and schemas are included any non-conformant elements or attributes on the incoming XML stream.
herein for descriptive purposes only. Validation of XML streams and stanzas is NOT REQUIRED or recommended,
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
[25]) and UTF-16 (RFC 2781 [26]) transformations of Universal [18]) and UTF-16 (RFC 2781 [19]) transformations of Universal
Character Set (ISO/IEC 10646-1 [27]) characters. Software MUST NOT Character Set (ISO/IEC 10646-1 [20]) characters. Software MUST NOT
attempt to use any other encoding for transmitted data. The encodings attempt to use any other encoding for transmitted data. The
of the transmitted and received streams are independent. Software MAY encodings of the transmitted and received streams are independent.
select either UTF-8 or UTF-16 for the transmitted stream, and SHOULD Software MAY select either UTF-8 or UTF-16 for the transmitted
deduce the encoding of the received stream as described in the XML stream, and SHOULD deduce the encoding of the received stream as
specification [1]. For historical reasons, existing implementations described in the XML specification [1]. For historical reasons,
MAY support UTF-8 only. existing implementations MAY support UTF-8 only.
8.5 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 Stream Errors 9.1 XML Namespace Name for TLS Data
A URN sub-namespace for TLS-related data in XMPP is defined as
follows.
URI: urn:ietf:params:xml:ns:xmpp-tls
Specification: [RFCXXXX]
Description: This is the XML namespace name for TLS-related data in
XMPP as defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
9.2 XML Namespace Name for SASL Data
A URN sub-namespace for SASL-related data in XMPP is defined as
follows.
URI: urn:ietf:params:xml:ns:xmpp-sasl
Specification: [RFCXXXX]
Description: This is the XML namespace name for SASL-related data in
XMPP as defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
9.3 XML Namespace Name for Stream Errors
A URN sub-namespace for XMPP stream error tags is defined as follows. A URN sub-namespace for XMPP stream error tags is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-streams URI: urn:ietf:params:xml:ns:xmpp-streams
Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for XMPP stream errors as Description: This is the XML namespace name for XMPP stream errors 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>
9.2 XML Namespace Name for Stanza Errors 9.4 XML Namespace Name for Stanza Errors
A URN sub-namespace for XMPP stanza error tags is defined as follows. A URN sub-namespace for XMPP stanza error tags is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-stanzas URI: urn:ietf:params:xml:ns:xmpp-stanzas
Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for XMPP stanza errors as Description: This is the XML namespace name for XMPP stanza errors 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>
9.3 Existing Registrations 9.5 Existing Registrations
The IANA registers "xmpp" as a GSSAPI [29] service name, as specified The IANA registers "xmpp" as a GSSAPI [21] 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 For the purposes of XMPP communications (client-to-server and server-
server-to-server), the term "high security" refers to the use of to-server), the term "high security" refers to the use of security
security technologies that provide both mutual authentication and technologies that provide both mutual authentication and integrity-
integrity-checking; in particular, when using certificate-based checking; in particular, when using certificate-based authentication
authentication to provide high security, a chain-of-trust must be to provide high security, a chain-of-trust SHOULD be established out-
established out-of-band (i.e., self-signed certificates are not of-band, although a shared certificate authority signing certificates
sufficient). could allow a previously unknown certificate to establish trust in-
band.
Self-signed certificates MAY be used but pose a problem for
administrators the first time such a certificate is seen. A self-
signed certificate, if accepted, MUST be stored by an entity in order
to verify in future communications. A server that changes its self-
signed cert to another self-signed cert (or to a certificate signed
by an unrecognized authority) therefore creates administration
problems for all entities with which it has communicated before and
will again. In particular, those entities have no reason to believe
that the new self-signed cert was not generated by an attacker to
impersonate the previously-trusted server.
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.
skipping to change at page 52, line 38 skipping to change at page 59, line 50
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 [28]. End-to-End Object Encryption in XMPP [31].
11.3 Server-to-Server Communications 11.3 Server-to-Server Communications
A compliant implementation MUST support both TLS and SASL for A compliant implementation MUST support both TLS and SASL for inter-
inter-domain communications. For historical reasons, a compliant 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 for any given domain to communicate with other domains, and server-
server-to-server communications MAY be disabled by the administrator to-server communications MAY be disabled by the administrator of any
of any given deployment. If a particular domain enables inter-domain 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
communications in order to ensure authentication and confidentiality
(e.g., on an organization's private network). Compliant
implementations SHOULD support SASL for this purpose.
11.4 Firewalls 11.4 Firewalls
Communications using XMPP normally occur over TCP sockets on port Communications using XMPP normally occur over TCP sockets on port
5222 (client-to-server) or port 5269 (server-to-server), as 5222 (client-to-server) or port 5269 (server-to-server), as
registered with the IANA [6]. Use of these well-known ports allows registered with the IANA [5]. Use of these well-known ports allows
administrators to easily enable or disable XMPP activity through administrators to easily enable or disable XMPP activity through
existing and commonly-deployed firewalls. existing and commonly-deployed firewalls.
11.5 Mandatory to Implement Technologies 11.5 Mandatory to Implement Technologies
At a minimum, all implementations MUST support the following At a minimum, all implementations MUST support the following
mechanisms: mechanisms:
for authentication: the SASL DIGEST-MD5 mechanism for authentication: the SASL DIGEST-MD5 mechanism
for confidentiality: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA for confidentiality: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA
cipher) cipher)
for both: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher for both: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher
supporting client-side certificates) supporting client-side certificates)
References Normative References
[1] World Wide Web Consortium, "Extensible Markup Language (XML) [1] World Wide Web Consortium, "Extensible Markup Language (XML)
1.0 (Second Edition)", W3C xml, October 2000, <http:// 1.0 (Second Edition)", W3C xml, October 2000, <http://
www.w3.org/TR/2000/REC-xml-20001006>. www.w3.org/TR/2000/REC-xml-20001006>.
[2] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging [2] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for
(draft-ietf-xmpp-im-08, work in progress)", April 2003.
[3] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for
Presence and Instant Messaging", RFC 2779, February 2000, Presence and Instant Messaging", RFC 2779, February 2000,
<http://www.ietf.org/rfc/rfc2779.txt>. <http://www.ietf.org/rfc/rfc2779.txt>.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[5] University of Southern California, "Transmission Control [4] University of Southern California, "Transmission Control
Protocol", RFC 793, September 1981, <http://www.ietf.org/rfc/ Protocol", RFC 793, September 1981, <http://www.ietf.org/rfc/
rfc0793.txt>. rfc0793.txt>.
[6] Internet Assigned Numbers Authority, "Internet Assigned Numbers [5] Internet Assigned Numbers Authority, "Internet Assigned Numbers
Authority", January 1998, <http://www.iana.org/>. Authority", January 1998, <http://www.iana.org/>.
[7] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [6] Harrenstien, K., Stahl, M. and E. Feinler, "DoD Internet host
Resource Identifiers (URI): Generic Syntax", RFC 2396, August
1998, <http://www.ietf.org/rfc/rfc2396.txt>.
[8] Harrenstien, K., Stahl, M. and E. Feinler, "DoD Internet host
table specification", RFC 952, October 1985. table specification", RFC 952, October 1985.
[9] Braden, R., "Requirements for Internet Hosts - Application and [7] Braden, R., "Requirements for Internet Hosts - Application and
Support", STD 3, RFC 1123, October 1989. Support", STD 3, RFC 1123, October 1989.
[10] 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.
[11] 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.
[12] 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 Profile for Node Identifiers in XMPP (draft-ietf-xmpp-nodeprep-
(draft-ietf-xmpp-nodeprep-01, work in progress)", February 01, work in progress)", February 2003.
2003.
[13] Saint-Andre, P. and J. Hildebrand, "Resourceprep: A Stringprep
Profile for Resource Identifiers in XMPP
(draft-ietf-xmpp-resourceprep-01, work in progress)", February
2003.
[14] World Wide Web Consortium, "Namespaces in XML", W3C xml-names, [11] Saint-Andre, P. and J. Hildebrand, "Resourceprep: A Stringprep
January 1999, <http://www.w3.org/TR/1999/ Profile for Resource Identifiers in XMPP (draft-ietf-xmpp-
REC-xml-names-19990114/>. resourceprep-01, work in progress)", February 2003.
[15] Mealling, M., "The IANA XML Registry", [12] World Wide Web Consortium, "Namespaces in XML", W3C xml-names,
draft-mealling-iana-xmlns-registry-04 (work in progress), June January 1999, <http://www.w3.org/TR/1999/REC-xml-names-
2002. 19990114/>.
[16] 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.
[17] Crispin, M., "Internet Message Access Protocol - Version [14] Myers, J., "Simple Authentication and Security Layer (SASL)",
4rev1", RFC 2060, December 1996.
[18] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD
53, RFC 1939, May 1996.
[19] Newman, C. and J. Myers, "ACAP -- Application Configuration
Access Protocol", RFC 2244, November 1997.
[20] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595,
June 1999.
[21] Myers, J., "Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997. RFC 2222, October 1997.
[22] Alvestrand, H., "Tags for the Identification of Languages", BCP [15] Leach, P. and C. Newman, "Using Digest Authentication as a SASL
Mechanism", RFC 2831, May 2000.
[16] Alvestrand, H., "Tags for the Identification of Languages", BCP
47, RFC 3066, January 2001. 47, RFC 3066, January 2001.
[23] Gulbrandsen, A. and P. Vixie, "A DNS RR for specifying the [17] 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.
[24] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., [18] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999.
[25] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998. 2279, January 1998.
[26] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646", [19] Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO 10646",
RFC 2781, February 2000. RFC 2781, February 2000.
[27] International Organization for Standardization, "Information [20] 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.
[28] Saint-Andre, P. and J. Hildebrand, "End-to-End Object [21] Linn, J., "Generic Security Service Application Program
Encryption in XMPP (draft-ietf-xmpp-e2e-00, work in progress)",
February 2003.
[29] Linn, J., "Generic Security Service Application Program
Interface, Version 2", RFC 2078, January 1997. Interface, Version 2", RFC 2078, January 1997.
Informative References
[22] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging (draft-
ietf-xmpp-im-08, work in progress)", April 2003.
[23] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, August
1998, <http://www.ietf.org/rfc/rfc2396.txt>.
[24] Mealling, M., "The IANA XML Registry", draft-mealling-iana-
xmlns-registry-04 (work in progress), June 2002.
[25] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 2060, December 1996.
[26] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD
53, RFC 1939, May 1996.
[27] Newman, C. and J. Myers, "ACAP -- Application Configuration
Access Protocol", RFC 2244, November 1997.
[28] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595,
June 1999.
[29] Eastlake, D., "Domain Name System Security Extensions", RFC
2535, March 1999.
[30] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L.,
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999.
[31] Saint-Andre, P. and J. Hildebrand, "End-to-End Object
Encryption in XMPP (draft-ietf-xmpp-e2e-01, work in progress)",
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
Jeremie Miller Jeremie Miller
Jabber Software Foundation Jabber Software Foundation
EMail: jeremie@jabber.org EMail: jeremie@jabber.org
URI: http://www.jabber.org/people/jer.php URI: http://www.jabber.org/people/jer.php
Appendix A. XML Schemas Appendix A. XML Schemas
The following XML schemas are descriptive, not normative. The following XML schemas are descriptive, not normative.
skipping to change at page 58, line 22 skipping to change at page 66, line 22
</xs:element> </xs:element>
</xs:schema> </xs:schema>
A.2 TLS namespace A.2 TLS 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.ietf.org/rfc/rfc2595.txt' targetNamespace='urn:ietf:params:xml:ns:xmpp-tls'
xmlns='http://www.ietf.org/rfc/rfc2595.txt' xmlns='urn:ietf:params:xml:ns:xmpp-tls'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='starttls'/> <xs:element name='starttls'>
<xs:complexType>
<xs:element ref='required' maxOccurs='1'>
</xs:complexType>
</xs:element>
<xs:element name='proceed'/> <xs:element name='proceed'/>
<xs:element name='failure'/> <xs:element name='failure'/>
<xs:element name='required'/>
</xs:schema> </xs:schema>
A.3 SASL namespace A.3 SASL 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.iana.org/assignments/sasl-mechanisms' targetNamespace='urn:ietf:params:xml:ns:xmpp-sasl'
xmlns='http://www.iana.org/assignments/sasl-mechanisms' xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='mechanisms'> <xs:element name='mechanisms'>
<xs:complexType> <xs:complexType>
<xs:element ref='mechanism' maxOccurs='unbounded'> <xs:element ref='mechanism' maxOccurs='unbounded'>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='mechanism' type='xs:string'/> <xs:element name='mechanism' type='xs:string'/>
<xs:element name='auth'> <xs:element name='auth'>
<xs:complexType> <xs:complexType>
<xs:attribute name='mechanism' type='xs:string' use='optional'/> <xs:attribute name='mechanism'
type='xs:string' use='optional'/>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='challenge' type='xs:string'/> <xs:element name='challenge' type='xs:string'/>
<xs:element name='response' type='xs:string'/> <xs:element name='response' type='xs:string'/>
<xs:element name='abort'/> <xs:element name='abort'/>
<xs:element name='success'/> <xs:element name='success'/>
<xs:element name='failure'> <xs:element name='failure'>
<xs:complexType> <xs:complexType>
<xs:attribute name='code' type='xs:string' use='optional'/> <xs:choice>
<xs:element ref='auth-mechanism-too-weak' maxOccurs='1'>
<xs:element ref='invalid-realm' maxOccurs='1'>
<xs:element ref='password-transition-required' maxOccurs='1'>
<xs:element ref='resource-conflict' maxOccurs='1'>
<xs:element ref='temporary-auth-failure' maxOccurs='1'>
<xs:element ref='user-not-authorized' maxOccurs='1'>
</xs:choice>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='auth-mechanism-too-weak'/>
<xs:element name='invalid-realm'/>
<xs:element name='password-transition-required'/>
<xs:element name='resource-conflict'/>
<xs:element name='temporary-auth-failure'/>
<xs:element name='user-not-authorized'/>
</xs:schema> </xs:schema>
A.4 Dialback namespace A.4 Dialback 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='jabber:server:dialback' targetNamespace='jabber:server:dialback'
xmlns='jabber:server:dialback' xmlns='jabber:server:dialback'
skipping to change at page 61, line 4 skipping to change at page 69, line 7
A.5 Client namespace A.5 Client 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='jabber:client' targetNamespace='jabber:client'
xmlns='jabber:client' xmlns='jabber:client'
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' minOccurs='0' maxOccurs='unbounded'/> <xs:element ref='body'
<xs:element ref='subject' minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='subject'
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='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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' 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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/>
</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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/>
</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' minOccurs='0' maxOccurs='unbounded'/> <xs:element ref='status'
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'/>
<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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' 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 62, line 40 skipping to change at page 71, line 4
<xs:element name='show'> <xs:element name='show'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/>
</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:choice maxOccurs='unbounded'> <xs:choice maxOccurs='unbounded'>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
skipping to change at page 63, line 43 skipping to change at page 72, line 7
<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='http://www.jabber.org/protocol'
xmlns='http://www.jabber.org/protocol' xmlns='http://www.jabber.org/protocol'
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' minOccurs='0' maxOccurs='unbounded'/> <xs:element ref='body'
<xs:element ref='subject' minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='subject'
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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' 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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/>
</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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/>
</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' minOccurs='0' maxOccurs='unbounded'/> <xs:element ref='status'
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'/>
<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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' 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 65, line 47 skipping to change at page 74, line 24
<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' type='xs:NMTOKEN' use='optional'/> <xs:attribute name='xml:lang'
type='xmlLangType' use='optional'/>
</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:choice maxOccurs='unbounded'> <xs:choice maxOccurs='unbounded'>
<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'/>
skipping to change at page 66, line 46 skipping to change at page 75, line 25
<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'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='stream-condition'> <xs:element name='stream-condition'>
<xs:complexType> <xs:complexType>
<xs:any <xs:any
namespace='##other' namespace='##other'
skipping to change at page 67, line 20 skipping to change at page 76, line 6
<xs:element name='stream-condition'> <xs:element name='stream-condition'>
<xs:complexType> <xs:complexType>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='1'/> maxOccurs='1'/>
<xs:choice maxOccurs='1'> <xs:choice maxOccurs='1'>
<xs:element ref='host-gone'/> <xs:element ref='host-gone'/>
<xs:element ref='host-unknown'/> <xs:element ref='host-unknown'/>
<xs:element ref='internal-server-error'/> <xs:element ref='internal-server-error'/>
<xs:element ref='invalid-id'/>
<xs:element ref='invalid-namespace'/> <xs:element ref='invalid-namespace'/>
<xs:element ref='nonmatching-hosts'/>
<xs:element ref='remote-connection-failed'/>
<xs:element ref='resource-constraint'/> <xs:element ref='resource-constraint'/>
<xs:element ref='see-other-host'/> <xs:element ref='see-other-host'/>
<xs:element ref='system-shutdown'/> <xs:element ref='system-shutdown'/>
<xs:element ref='unsupported-stanza-type'/> <xs:element ref='unsupported-stanza-type'/>
<xs:element ref='unsupported-version'/> <xs:element ref='unsupported-version'/>
<xs:element ref='xml-not-well-formed'/> <xs:element ref='xml-not-well-formed'/>
</xs:choice> </xs:choice>
</xs:complexType> </xs:complexType>
<xs:element name='host-gone' type='xs:string'/> <xs:element name='host-gone'/>
<xs:element name='host-unknown' type='xs:string'/> <xs:element name='host-unknown'/>
<xs:element name='internal-server-error' type='xs:string'/> <xs:element name='internal-server-error'/>
<xs:element name='invalid-namespace' type='xs:string'/> <xs:element name='invalid-id'/>
<xs:element name='resource-constraint' type='xs:string'/> <xs:element name='invalid-namespace'/>
<xs:element name='see-other-host' type='xs:string'/> <xs:element name='nonmatching-hosts'/>
<xs:element name='system-shutdown' type='xs:string'/> <xs:element name='remote-connection-failed'/>
<xs:element name='unsupported-stanza-type' type='xs:string'/> <xs:element name='resource-constraint'/>
<xs:element name='unsupported-version' type='xs:string'/> <xs:element name='see-other-host'/>
<xs:element name='xml-not-well-formed' type='xs:string'/> <xs:element name='system-shutdown'/>
<xs:element name='unsupported-stanza-type'/>
<xs:element name='unsupported-version'/>
<xs:element name='xml-not-well-formed'/>
</xs:schema> </xs:schema>
A.8 Stanza error namespace A.8 Stanza 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-stanzas' targetNamespace='urn:ietf:params:xml:ns:xmpp-stanzas'
skipping to change at page 68, line 28 skipping to change at page 77, line 20
<xs:element ref='jid-not-found'/> <xs:element ref='jid-not-found'/>
<xs:element ref='not-allowed'/> <xs:element ref='not-allowed'/>
<xs:element ref='recipient-unavailable'/> <xs:element ref='recipient-unavailable'/>
<xs:element ref='registration-required'/> <xs:element ref='registration-required'/>
<xs:element ref='remote-server-not-found'/> <xs:element ref='remote-server-not-found'/>
<xs:element ref='remove-server-timeout'/> <xs:element ref='remove-server-timeout'/>
<xs:element ref='service-unavailable'/> <xs:element ref='service-unavailable'/>
</xs:choice> </xs:choice>
</xs:complexType> </xs:complexType>
<xs:element name='bad-request' type='xs:string'/> <xs:element name='bad-request'/>
<xs:element name='feature-not-implemented' type='xs:string'/> <xs:element name='feature-not-implemented'/>
<xs:element name='forbidden' type='xs:string'/> <xs:element name='forbidden'/>
<xs:element name='internal-server-error' type='xs:string'/> <xs:element name='internal-server-error'/>
<xs:element name='jid-malformed' type='xs:string'/> <xs:element name='jid-malformed'/>
<xs:element name='jid-not-found' type='xs:string'/> <xs:element name='jid-not-found'/>
<xs:element name='not-allowed' type='xs:string'/> <xs:element name='not-allowed'/>
<xs:element name='recipient-unavailable' type='xs:string'/> <xs:element name='recipient-unavailable'/>
<xs:element name='registration-required' type='xs:string'/> <xs:element name='registration-required'/>
<xs:element name='remote-server-not-found' type='xs:string'/> <xs:element name='remote-server-not-found'/>
<xs:element name='remote-server-timeout' type='xs:string'/> <xs:element name='remote-server-timeout'/>
<xs:element name='service-unavailable' type='xs:string'/> <xs:element name='service-unavailable'/>
</xs:schema> </xs:schema>
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-07 B.1 Changes from draft-ietf-xmpp-core-08
o Incorporated list discussion regarding addressing, SASL, TLS, TCP,
dialback, namespaces, extensibility, and the meaning of 'ignore'
for routers and recipients.
o Specified dialback error conditions.
o Made small editorial changes to address RFC Editor requirements.
B.2 Changes from draft-ietf-xmpp-core-07
o Made several small editorial changes. o Made several small editorial changes.
B.2 Changes from draft-ietf-xmpp-core-06 B.3 Changes from draft-ietf-xmpp-core-06
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 [15]. to the format defined in The IETF XML Registry [24].
o Removed note to RFC editor regarding provisional namespace names. o Removed note to RFC editor regarding provisional namespace names.
B.3 Changes from draft-ietf-xmpp-core-05 B.4 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.
B.4 Changes from draft-ietf-xmpp-core-04 B.5 Changes from draft-ietf-xmpp-core-04
o Added server-to-server examples for TLS and SASL. o Added server-to-server examples for TLS and SASL.
o Changed error syntax, rules, and examples based on list o Changed error syntax, rules, and examples based on list
discussion. discussion.
o Added schemas for the TLS, stream error, and stanza error o Added schemas for the TLS, stream error, and stanza error
namespaces. namespaces.
o Added note to RFC editor regarding provisional namespace names. o Added note to RFC editor regarding provisional namespace names.
o Made numerous small editorial changes and clarified text o Made numerous small editorial changes and clarified text
throughout. throughout.
B.5 Changes from draft-ietf-xmpp-core-03 B.6 Changes from draft-ietf-xmpp-core-03
o Clarified rules and procedures for TLS and SASL. o Clarified rules and procedures for TLS and SASL.
o Amplified stream error code syntax per list discussion. o Amplified stream error code syntax per list discussion.
o Made numerous small editorial changes. o Made numerous small editorial changes.
B.6 Changes from draft-ietf-xmpp-core-02 B.7 Changes from draft-ietf-xmpp-core-02
o Added dialback schema. o Added dialback schema.
o Removed all DTDs since schemas provide more complete definitions. o Removed all DTDs since schemas provide more complete definitions.
o Added stream error codes. o Added stream error codes.
o Clarified error code "philosophy". o Clarified error code "philosophy".
B.7 Changes from draft-ietf-xmpp-core-01 B.8 Changes from draft-ietf-xmpp-core-01
o Updated the addressing restrictions per list discussion and added o Updated the addressing restrictions per list discussion and added
references to the new nodeprep and resourceprep profiles. references to the new nodeprep and resourceprep profiles.
o Corrected error in Stream Authentication regarding "version='1.0'" o Corrected error in Stream Authentication regarding "version='1.0'"
flag. flag.
o Made numerous small editorial changes. o Made numerous small editorial changes.
B.8 Changes from draft-ietf-xmpp-core-00 B.9 Changes from draft-ietf-xmpp-core-00
o Added information about TLS from list discussion. o Added information about TLS from list discussion.
o Clarified meaning of "ignore" based on list discussion. o Clarified meaning of "ignore" based on list discussion.
o Clarified information about Universal Character Set data and o Clarified information about Universal Character Set data and
character encodings. character encodings.
o Provided base64-decoded information for examples. o Provided base64-decoded information for examples.
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
o Made numerous small editorial fixes. o Made numerous small editorial fixes.
B.9 Changes from draft-miller-xmpp-core-02 B.10 Changes from draft-miller-xmpp-core-02
o Brought Streams Authentication section into line with discussion o Brought Streams Authentication section into line with discussion
on list and at IETF 55 meeting. on list and at IETF 55 meeting.
o Added information about the optional 'xml:lang' attribute per o Added information about the optional 'xml:lang' attribute per
discussion on list and at IETF 55 meeting. discussion on list and at IETF 55 meeting.
o Specified that validation is neither required nor recommended, and o Specified that validation is neither required nor recommended, and
that the formal definitions (DTDs and schemas) are included for that the formal definitions (DTDs and schemas) are included for
descriptive purposes only. descriptive purposes only.
skipping to change at page 72, line 5 skipping to change at page 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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