draft-ietf-xmpp-core-19.txt   draft-ietf-xmpp-core-20.txt 
Network Working Group P. Saint-Andre XMPP Working Group P. Saint-Andre (ed.)
Internet-Draft J. Miller Internet-Draft Jabber Software Foundation
Expires: April 25, 2004 Jabber Software Foundation Expires: May 20, 2004 November 20, 2003
October 26, 2003
XMPP Core Extensible Messaging and Presence Protocol (XMPP): Core
draft-ietf-xmpp-core-19 draft-ietf-xmpp-core-20
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract Abstract
This memo defines the core features of the Extensible Messaging and This memo defines the core features of the Extensible Messaging and
Presence Protocol (XMPP), a protocol for streaming XML [1] elements Presence Protocol (XMPP), a protocol for streaming Extensible Markup
in order to exchange messages and presence information in close to Language (XML) elements in order to exchange structured information
real time. While XMPP provides a generalized, extensible framework in close to real time between any two network endpoints. While XMPP
for transporting structured information, it is used mainly for the provides a generalized, extensible framework for exchanging XML data,
purpose of building instant messaging and presence applications that it is used mainly for the purpose of building instant messaging and
meet the requirements of RFC 2779. presence applications that meet the requirements of RFC 2779.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Generalized Architecture . . . . . . . . . . . . . . . . . . . 4
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Discussion Venue . . . . . . . . . . . . . . . . . . . . . 6 4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4 Intellectual Property Notice . . . . . . . . . . . . . . . 6 5. Use of TLS . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2. Generalized Architecture . . . . . . . . . . . . . . . . . 6 6. Use of SASL . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Resource Binding . . . . . . . . . . . . . . . . . . . . . . . 36
2.2 Server . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. Server Dialback . . . . . . . . . . . . . . . . . . . . . . . 39
2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . 8 10. Server Rules for Handling XML Stanzas . . . . . . . . . . . . 54
2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . 8 11. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . . 57
3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . 8 12. Core Compliance Requirements . . . . . . . . . . . . . . . . . 59
3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 8 13. Internationalization Considerations . . . . . . . . . . . . . 61
3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . 9 14. Security Considerations . . . . . . . . . . . . . . . . . . . 61
3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . 9 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 65
3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . 9 Normative References . . . . . . . . . . . . . . . . . . . . . 68
3.5 Formal Syntax . . . . . . . . . . . . . . . . . . . . . . 10 Informative References . . . . . . . . . . . . . . . . . . . . 70
3.6 Determination of Addresses . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 71
4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . 11 A. Nodeprep . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 11 B. Resourceprep . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.2 Stream Attributes . . . . . . . . . . . . . . . . . . . . 13 C. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.2.1 Version Support . . . . . . . . . . . . . . . . . . . . . 14 D. Differences Between Core Jabber Protocol and XMPP . . . . . . 82
4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . 15 E. Revision History . . . . . . . . . . . . . . . . . . . . . . . 84
4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . 92
4.5 Stream Encryption and Authentication . . . . . . . . . . . 15
4.6 Stream Errors . . . . . . . . . . . . . . . . . . . . . . 15
4.6.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6.3 Defined Conditions . . . . . . . . . . . . . . . . . . . . 17
4.6.4 Application-Specific Conditions . . . . . . . . . . . . . 19
4.7 Simplified Stream Examples . . . . . . . . . . . . . . . . 19
5. Stream Encryption . . . . . . . . . . . . . . . . . . . . 21
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . 24
5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . 26
6. Stream Authentication . . . . . . . . . . . . . . . . . . 28
6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 29
6.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . 31
6.4 SASL Errors . . . . . . . . . . . . . . . . . . . . . . . 32
6.5 Client-to-Server Example . . . . . . . . . . . . . . . . . 33
6.6 Server-to-Server Example . . . . . . . . . . . . . . . . . 36
7. Resource Binding . . . . . . . . . . . . . . . . . . . . . 39
8. Server Dialback . . . . . . . . . . . . . . . . . . . . . 41
8.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.2 Order of Events . . . . . . . . . . . . . . . . . . . . . 42
8.3 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 44
9. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . 47
9.1 Common Attributes . . . . . . . . . . . . . . . . . . . . 48
9.1.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
9.1.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
9.1.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
9.1.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
9.1.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . 50
9.2 Basic Semantics . . . . . . . . . . . . . . . . . . . . . 50
9.2.1 Message Semantics . . . . . . . . . . . . . . . . . . . . 50
9.2.2 Presence Semantics . . . . . . . . . . . . . . . . . . . . 50
9.2.3 IQ Semantics . . . . . . . . . . . . . . . . . . . . . . . 51
9.3 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . 52
9.3.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 52
9.3.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.3.3 Defined Conditions . . . . . . . . . . . . . . . . . . . . 54
9.3.4 Application-Specific Conditions . . . . . . . . . . . . . 56
10. XML Usage within XMPP . . . . . . . . . . . . . . . . . . 57
10.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . 57
10.2 XML Namespace Names and Prefixes . . . . . . . . . . . . . 57
10.2.1 Streams Namespace . . . . . . . . . . . . . . . . . . . . 57
10.2.2 Default Namespace . . . . . . . . . . . . . . . . . . . . 58
10.2.3 Dialback Namespace . . . . . . . . . . . . . . . . . . . . 58
10.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . 59
10.4 Inclusion of Text Declaration . . . . . . . . . . . . . . 59
10.5 Character Encoding . . . . . . . . . . . . . . . . . . . . 59
11. IANA Considerations . . . . . . . . . . . . . . . . . . . 59
11.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . 59
11.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . 60
11.3 XML Namespace Name for Stream Errors . . . . . . . . . . . 60
11.4 XML Namespace Name for Resource Binding . . . . . . . . . 60
11.5 XML Namespace Name for Stanza Errors . . . . . . . . . . . 61
11.6 Nodeprep Profile of Stringprep . . . . . . . . . . . . . . 61
11.7 Resourceprep Profile of Stringprep . . . . . . . . . . . . 61
11.8 GSSAPI Service Name . . . . . . . . . . . . . . . . . . . 62
11.9 Port Numbers . . . . . . . . . . . . . . . . . . . . . . . 62
12. Internationalization Considerations . . . . . . . . . . . 62
13. Security Considerations . . . . . . . . . . . . . . . . . 62
13.1 High Security . . . . . . . . . . . . . . . . . . . . . . 62
13.2 Client-to-Server Communications . . . . . . . . . . . . . 63
13.3 Server-to-Server Communications . . . . . . . . . . . . . 64
13.4 Order of Layers . . . . . . . . . . . . . . . . . . . . . 65
13.5 Mandatory-to-Implement Technologies . . . . . . . . . . . 65
13.6 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . 65
13.7 Use of base64 in SASL . . . . . . . . . . . . . . . . . . 65
13.8 Stringprep Profiles . . . . . . . . . . . . . . . . . . . 66
14. Server Rules for Handling XML Stanzas . . . . . . . . . . 67
14.1 No 'to' Address . . . . . . . . . . . . . . . . . . . . . 67
14.2 Foreign Domain . . . . . . . . . . . . . . . . . . . . . . 67
14.3 Subdomain . . . . . . . . . . . . . . . . . . . . . . . . 68
14.4 Mere Domain or Specific Resource . . . . . . . . . . . . . 68
14.5 Node in Same Domain . . . . . . . . . . . . . . . . . . . 68
15. Compliance Requirements . . . . . . . . . . . . . . . . . 69
15.1 Servers . . . . . . . . . . . . . . . . . . . . . . . . . 69
15.2 Clients . . . . . . . . . . . . . . . . . . . . . . . . . 69
Normative References . . . . . . . . . . . . . . . . . . . 70
Informative References . . . . . . . . . . . . . . . . . . 71
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 72
A. Nodeprep . . . . . . . . . . . . . . . . . . . . . . . . . 72
A.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 72
A.2 Character Repertoire . . . . . . . . . . . . . . . . . . . 73
A.3 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 73
A.4 Normalization . . . . . . . . . . . . . . . . . . . . . . 73
A.5 Prohibited Output . . . . . . . . . . . . . . . . . . . . 73
A.6 Bidirectional Characters . . . . . . . . . . . . . . . . . 74
B. Resourceprep . . . . . . . . . . . . . . . . . . . . . . . 74
B.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 75
B.2 Character Repertoire . . . . . . . . . . . . . . . . . . . 75
B.3 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 75
B.4 Normalization . . . . . . . . . . . . . . . . . . . . . . 75
B.5 Prohibited Output . . . . . . . . . . . . . . . . . . . . 76
B.6 Bidirectional Characters . . . . . . . . . . . . . . . . . 76
C. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . 76
C.1 Streams namespace . . . . . . . . . . . . . . . . . . . . 76
C.2 Stream error namespace . . . . . . . . . . . . . . . . . . 78
C.3 TLS namespace . . . . . . . . . . . . . . . . . . . . . . 79
C.4 SASL namespace . . . . . . . . . . . . . . . . . . . . . . 79
C.5 Resource binding namespace . . . . . . . . . . . . . . . . 81
C.6 Dialback namespace . . . . . . . . . . . . . . . . . . . . 81
C.7 Stanza error namespace . . . . . . . . . . . . . . . . . . 82
D. Differences Between Core Jabber Protocol and XMPP . . . . 83
D.1 Channel Encryption . . . . . . . . . . . . . . . . . . . . 84
D.2 Authentication . . . . . . . . . . . . . . . . . . . . . . 84
D.3 Resource Binding . . . . . . . . . . . . . . . . . . . . . 84
D.4 JID Processing . . . . . . . . . . . . . . . . . . . . . . 84
D.5 Error Handling . . . . . . . . . . . . . . . . . . . . . . 85
D.6 Internationalization . . . . . . . . . . . . . . . . . . . 85
D.7 Stream Version Attribute . . . . . . . . . . . . . . . . . 85
E. Revision History . . . . . . . . . . . . . . . . . . . . . 85
E.1 Changes from draft-ietf-xmpp-core-18 . . . . . . . . . . . 85
E.2 Changes from draft-ietf-xmpp-core-17 . . . . . . . . . . . 86
E.3 Changes from draft-ietf-xmpp-core-16 . . . . . . . . . . . 87
E.4 Changes from draft-ietf-xmpp-core-15 . . . . . . . . . . . 87
E.5 Changes from draft-ietf-xmpp-core-14 . . . . . . . . . . . 87
E.6 Changes from draft-ietf-xmpp-core-13 . . . . . . . . . . . 88
E.7 Changes from draft-ietf-xmpp-core-12 . . . . . . . . . . . 88
E.8 Changes from draft-ietf-xmpp-core-11 . . . . . . . . . . . 88
E.9 Changes from draft-ietf-xmpp-core-10 . . . . . . . . . . . 89
E.10 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . 89
E.11 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . 89
E.12 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . 89
E.13 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . 90
E.14 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . 90
E.15 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . 90
E.16 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . 90
E.17 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . 91
E.18 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . 91
E.19 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . 91
E.20 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . 91
Intellectual Property and Copyright Statements . . . . . . 93
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 [XML] protocol for near-real-time messaging, presence, and
request-response services. The basic syntax and semantics were request-response services. The basic syntax and semantics were
developed originally within the Jabber open-source community, mainly developed originally within the Jabber open-source community, mainly
in 1999. In 2002, the XMPP WG was chartered with developing an in 1999. In 2002, the XMPP WG was chartered with developing an
adaptation of the Jabber protocol that would be suitable as an IETF adaptation of the Jabber protocol that would be suitable as an IETF
instant messaging (IM) and presence technology. As a result of work instant messaging (IM) and presence technology. As a result of work
by the XMPP WG, the current memo defines the core features of XMPP; by the XMPP WG, the current memo defines the core features of XMPP;
XMPP IM [21] defines the extensions required to provide the instant Extensible Messaging and Presence Protocol (XMPP): Instant Messaging
messaging and presence functionality defined in RFC 2779 [2]. and Presence [XMPP-IM] defines the extensions required to provide the
instant messaging and presence functionality defined in RFC 2779
[IMP-REQS].
1.2 Terminology 1.2 Terminology
The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC "OPTIONAL" in this document are to be interpreted as described in RFC
2119 [3]. 2119 [TERMS].
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
This document is in full compliance with all provisions of Section 10 This document is in full compliance with all provisions of Section 10
of RFC 2026. Parts of this specification use the term "jabber" for of RFC 2026. Parts of this specification use the term "jabber" for
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.
1.5 Contributors
Most of the core aspects of the Extensible Messaging and Presence
Protocol were developed originally within the Jabber open-source
community in 1999. This community was founded by Jeremie Miller, who
released source code for the initial version of the jabberd server in
January 1999. Major early contributors to the base protocol also
included Ryan Eatmon, Peter Millard, Thomas Muldowney, and Dave
Smith. Work by the XMPP Working Group has concentrated especially on
security and internationalization; in these areas, protocols for the
use of TLS and SASL were originally contributed by Rob Norris, and
stringprep profiles were originally contributed by Joe Hildebrand.
The error code syntax was suggested by Lisa Dusseault.
1.6 Acknowledgements
Thanks are due to a number of individuals in addition to the
contributors listed. Although it is difficult to provide a complete
list, the following individuals were particularly helpful in defining
the protocols or in commenting on the specifications in this memo:
Thomas Charron, Richard Dobson, Sam Hartman, Schuyler Heath, Jonathan
Hogg, Craig Kaes, Jacek Konieczny, Alexey Melnikov, Keith Minkler,
Julian Missig, Pete Resnick, Marshall Rose, Alexey Shchepin,
Jean-Louis Seguineau, Iain Shigeoka, and David Waite. Thanks also to
members of the XMPP Working Group and the IETF community for comments
and feedback provided throughout the life of this memo.
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
date it usually has been implemented via a typical client-server date it usually has been implemented via a typical client-server
architecture, wherein a client utilizing XMPP accesses a server over architecture, wherein a client utilizing XMPP accesses a server over
a TCP [4] socket. a TCP [TCP] 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 23 skipping to change at page 5, line 4
The symbols are as follows: The symbols are as follows:
o C1, C2, C3 -- XMPP clients o C1, C2, C3 -- XMPP clients
o S1, S2 -- XMPP servers o S1, S2 -- XMPP servers
o G1 -- A gateway that translates between XMPP and the protocol(s) o G1 -- A gateway that translates between XMPP and the protocol(s)
used on a foreign (non-XMPP) messaging network used on a foreign (non-XMPP) messaging network
o FN1 -- A foreign messaging network o FN1 -- A foreign messaging network
o FC1 -- A client on a foreign messaging network o FC1 -- A client on a foreign messaging network
2.2 Server 2.2 Server
A server acts as an intelligent abstraction layer for XMPP A server acts as an intelligent abstraction layer for XMPP
communications. Its primary responsibilities are to manage communications. Its primary responsibilities are:
connections from or sessions for other entities (in the form of XML
streams (Section 4) to and from authorized clients, servers, and o to manage connections from or sessions for other entities, in the
other entities) and to route appropriately-addressed XML stanzas form of XML streams (Section 4) to and from authorized clients,
(Section 9) among such entities over XML streams. Most XMPP-compliant servers, and other entities
servers also assume responsibility for the storage of data that is
used by clients (e.g., contact lists for users of XMPP-based instant o to route appropriately-addressed XML stanzas (Section 9) among
messaging and presence applications); in this case, the XML data is such entities over XML streams
processed directly by the server itself on behalf of the client and
is not routed to another entity. Compliant server implementations Most XMPP-compliant servers also assume responsibility for the
MUST ensure in-order processing of XML stanzas between any two storage of data that is used by clients (e.g., contact lists for
entities. users of XMPP-based instant messaging and presence applications); in
this case, the XML data is processed directly by the server itself on
behalf of the client and is not routed to another entity.
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 there is no necessary coupling and any associated services. Although there is no necessary coupling
of an XML stream to a TCP socket (e.g., a client COULD connect via of an XML stream to a TCP socket (e.g., a client could connect via
HTTP [22] polling or some other mechanism), this specification HTTP [HTTP] polling or some other mechanism), this specification
defines a binding of XMPP to TCP only. Multiple resources (e.g., defines a binding of XMPP to TCP only. Multiple resources (e.g.,
devices or locations) MAY connect simultaneously to a server on devices or locations) MAY connect simultaneously to a server on
behalf of each authorized client, with each resource differentiated behalf of each authorized client, with each resource differentiated
by the resource identifier of a JID (e.g., <node@domain/home> vs. by the resource identifier of an XMPP address (e.g., <node@domain/
<node@domain/work>) as defined under Addressing Scheme (Section 3). home> vs. <node@domain/work>) as defined under Addressing Scheme
The RECOMMENDED port for connections between a client and a server is (Section 3). The RECOMMENDED port for connections between a client
5222, as registered with the Internet Assigned Numbers Authority and a server is 5222, as registered with the IANA (see Port Numbers
(IANA) [5] (see Port Numbers (Section 11.9)). (Section 15.9)).
2.4 Gateway 2.4 Gateway
A gateway is a special-purpose server-side service whose primary A gateway is a special-purpose server-side service whose primary
function is to translate XMPP into the protocol used by a foreign function is to translate XMPP into the protocol used by a foreign
(non-XMPP) messaging system, as well as to translate the return data (non-XMPP) messaging system, as well as to translate the return data
back into XMPP. Examples are gateways to Internet Relay Chat (IRC), back into XMPP. Examples are gateways to Internet Relay Chat (IRC),
Short Message Service (SMS), SIMPLE, SMTP, and legacy instant Short Message Service (SMS), SIMPLE, SMTP, and legacy instant
messaging networks such as AIM, ICQ, MSN Messenger, and Yahoo! messaging networks such as AIM, ICQ, MSN Messenger, and Yahoo!
Instant Messenger. Communications between gateways and servers, and Instant Messenger. Communications between gateways and servers, and
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2.5 Network 2.5 Network
Because each server is identified by a network address and because Because each server is identified by a network address and because
server-to-server communications are a straightforward extension of server-to-server communications are a straightforward extension of
the client-to-server protocol, in practice the system consists of a the client-to-server protocol, in practice the system consists of a
network of servers that inter-communicate. Thus user-a@domain1 is network of servers that inter-communicate. Thus user-a@domain1 is
able to exchange messages, presence, and other information with able to exchange messages, presence, and other information with
user-b@domain2. This pattern is familiar from messaging protocols user-b@domain2. This pattern is familiar from messaging protocols
(such as SMTP) that make use of network addressing standards. (such as SMTP) that make use of network addressing standards.
Communications between any two servers are OPTIONAL. If enabled, such Communications between any two servers are OPTIONAL. If enabled,
communications SHOULD occur over XML streams that are bound to TCP such communications SHOULD occur over XML streams that are bound to
sockets. The RECOMMENDED port for connections between servers is [TCP] sockets. The RECOMMENDED port for connections between servers
5222, as registered with the Internet Assigned Numbers Authority is 5269, as registered with the IANA (see Port Numbers (Section
(IANA) [5] (see Port Numbers (Section 11.9)). 15.9)).
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 [23]. For historical reasons, the address of such an consistent with RFC 2396 [URI]. For historical reasons, the address
entity is called a Jabber Identifier or JID. A valid JID contains a of an XMPP entity is called a Jabber Identifier or JID. A valid JID
set of ordered elements formed of a domain identifier, node contains a set of ordered elements formed of a domain identifier,
identifier, and resource identifier in the following format: node identifier, and resource identifier. The syntax is defined below
[node@]domain[/resource]. Each allowable portion of a JID (node using Augmented Backus-Naur Form as defined in RFC 2234 [ABNF], where
identifier, domain identifier, and resource identifier) may be up to the "node", "domain", and "resource" identifiers are as specified in
1023 bytes in length, resulting in a maximum total size (including the following sections:
the '@' and '/' separators) of 3071 bytes.
All JIDs are based on the foregoing structure. The most common use of [ node "@" ] domain [ "/" resource ]
this structure is to identify an instant messaging user, the server
to which the user connects, and the user's active session or Each allowable portion of a JID (node identifier, domain identifier,
and resource identifier) MUST NOT be more than 1023 bytes in length,
resulting in a maximum total size (including the '@' and '/'
separators) of 3071 bytes.
All JIDs are based on the foregoing structure. The most common use
of this structure is to identify an instant messaging user, the
server to which the user connects, and the user's active session or
connection (e.g., a specific client) in the form of <user@host/ connection (e.g., a specific client) in the form of <user@host/
resource>. However, node types other than clients are possible; for resource>. However, node types other than clients are possible; for
example, a specific chat room offered by a multi-user chat service example, a specific chat room offered by a multi-user chat service
could be addressed as <room@service> (where "room" is the name of the could be addressed as <room@service> (where "room" is the name of the
chat room and "service" is the hostname of the multi-user chat chat room and "service" is the hostname of the multi-user chat
service) and a specific occupant of such a room could be addressed as service) and a specific occupant of such a room could be addressed as
<room@service/nick> (where "nick" is the occupant's room nickname). <room@service/nick> (where "nick" is the occupant's room nickname).
Many other JID types are possible (e.g., <domain/resource> could be a Many other JID types are possible (e.g., <domain/resource> could be a
server-side script or service). server-side script or service).
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REQUIRED element of a JID (a mere domain identifier is a valid JID). REQUIRED element of a JID (a mere domain identifier is a valid JID).
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 (e.g., a multi-user chat service, beyond the capabilities of a server (e.g., a multi-user chat service,
a user directory, or a gateway to a foreign messaging system). a user directory, or a gateway to a foreign messaging system).
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 be a Fully Qualified Domain Name.
Name. A domain identifier MUST be not more than 1023 bytes in length A domain identifier MUST be an "internationalized domain name" as
and MUST conform to the Nameprep [6] profile of stringprep [7]. defined in [IDNA], to which the Nameprep [NAMEPREP] profile of
stringprep [STRINGPREP] can be applied without failing. Before
comparing two domain identifiers, a server MUST (and a client SHOULD)
first apply the Nameprep profile to the labels (as defined in [IDNA])
that make up each identifier.
3.3 Node Identifier 3.3 Node Identifier
The node identifier is an optional secondary identifier placed before The node identifier is an optional secondary identifier placed before
the domain identifier and separated from the latter by the '@' the domain identifier and separated from the latter by the '@'
character. It usually represents the entity requesting and using character. It usually represents the entity requesting and using
network access provided by the server or gateway (i.e., a client), network access provided by the server or gateway (i.e., a client),
although it can also represent other kinds of entities (e.g., a chat although it can also represent other kinds of entities (e.g., a chat
room associated with a multi-user chat service). The entity room associated with a multi-user chat service). The entity
represented by a node identifier is addressed within the context of a represented by a node identifier is addressed within the context of a
specific domain; within instant messaging and presence applications specific domain; within instant messaging and presence applications
of XMPP this address is called a "bare JID" and is of the form of XMPP this address is called a "bare JID" and is of the form
<node@domain>. <node@domain>.
A node identifier MUST be no more than 1023 bytes in length and MUST A node identifier MUST be formatted such that the Nodeprep (Appendix
conform to the Nodeprep (Appendix A) profile of stringprep [7]. A) profile of [STRINGPREP] can be applied to it without failing.
Before comparing two node identifiers, a server MUST (and a client
SHOULD) first apply the Nodeprep profile to each identifier.
3.4 Resource Identifier 3.4 Resource Identifier
The resource identifier is an optional tertiary identifier placed The resource identifier is an optional tertiary identifier placed
after the domain identifier and separated from the latter by the '/' after the domain identifier and separated from the latter by the '/'
character. A resource identifier may modify either a <node@domain> or character. A resource identifier may modify either a <node@domain>
mere <domain> address. It usually represents a specific session, or mere <domain> address. It usually represents a specific session,
connection (e.g., a device or location), or object (e.g., a connection (e.g., a device or location), or object (e.g., a
participant in a multi-user chat room) belonging to the entity participant in a multi-user chat room) belonging to the entity
associated with a node identifier. A resource identifier is opaque to associated with a node identifier. A resource identifier is opaque
both servers and other clients, and is typically defined by a client to both servers and other clients, and is typically defined by a
implementation when it provides the information necessary to complete client implementation when it provides the information necessary to
Resource Binding (Section 7) (although it may be generated by a complete Resource Binding (Section 7) (although it may be generated
server on behalf of a client). An entity may maintain multiple by a server on behalf of a client). An entity MAY maintain multiple
resources simultaneously. resources simultaneously, with each resource differentiated by a
distinct resource identifier.
A resource identifier MUST be no more than 1023 bytes in length and
MUST conform to the Resourceprep (Appendix B) profile of stringprep
[7].
3.5 Formal Syntax
The syntax for a JID is defined below using Augmented Backus-Naur
Form as defined in RFC 2234 [8]. The IPv4address and IPv6address
rules are defined in Appendix B of RFC 2373 [9]; the hostname rule is
defined in Section 3.2.2 of RFC 2396 [23]; the allowable character
sequences that conform to the node rule are defined by the Nodeprep
(Appendix A) profile of stringprep [7] as documented in this memo;
the allowable character sequences that conform to the resource rule
are defined by the Resourceprep (Appendix B) profile of stringprep
[7] as documented in this memo.
jid = [ node "@" ] domain [ "/" resource ] A resource identifier MUST be formatted such that the Resourceprep
domain = hostname / IPv4address / IPv6address (Appendix B) profile of [STRINGPREP] can be applied to it without
failing. Before comparing two resource identifiers, a server MUST
(and a client SHOULD) first apply the Resourceprep profile to each
identifier.
3.6 Determination of Addresses 3.5 Determination of Addresses
After Stream Authentication (Section 6) and, if appropriate, Resource After SASL negotiation (Section 6) and, if appropriate, Resource
Binding (Section 7), the receiving entity for a stream MUST determine Binding (Section 7), the receiving entity for a stream MUST determine
the initiating entity's JID. the initiating entity's JID.
For server-to-server communications, the initiating entity's JID For server-to-server communications, the initiating entity's JID
SHOULD be the authorization identity, derived from the authentication SHOULD be the authorization identity, derived from the authentication
identity as defined in RFC 2222 [13] if no authorization identity was identity as defined by the Simple Authentication and Security Layer
specified during stream authentication. (SASL) specification [SASL] if no authorization identity was
specified during SASL negotiation (Section 6).
For client-to-server communications, the "bare JID" (<node@domain>) For client-to-server communications, the "bare JID" (<node@domain>)
SHOULD be the authorization identity, derived from the authentication SHOULD be the authorization identity, derived from the authentication
identity as defined in RFC 2222 [13] if no authorization identity was identity as defined in [SASL] if no authorization identity was
specified during stream authentication; the resource identifier specified during SASL negotiation (Section 6); the resource
portion of the "full JID" (<node@domain/resource>) SHOULD be the identifier portion of the "full JID" (<node@domain/resource>) SHOULD
resource identifier negotiated by the client and server during be the resource identifier negotiated by the client and server during
Resource Binding (Section 7). Resource Binding (Section 7).
The receiving entity MUST ensure that the resulting JID (including The receiving entity MUST ensure that the resulting JID (including
node identifier, domain identifier, resource identifier, and node identifier, domain identifier, resource identifier, and
separator characters) conforms to the rules and formats defined separator characters) conforms to the rules and formats defined
earlier in this section. earlier in this section; to meet this restriction, the receiving
entity may need to replace the JID sent by the initiating entity with
the canonicalized JID as determined by the receiving entity.
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. These between presence-aware entities: XML streams and XML stanzas. These
terms are defined as follows: terms are defined as follows:
Definition of XML Stream: An XML stream is a container for the Definition of XML Stream: An XML stream is a container for the
exchange of XML elements between any two entities over a network. exchange of XML elements between any two entities over a network.
An XML stream is negotiated from an initiating entity (usually a An XML stream is negotiated from an initiating entity (usually a
client or server) to a receiving entity (usually a server), client or server) to a receiving entity (usually a server),
normally over a TCP socket, and corresponds to the initiating normally over a [TCP] socket, and corresponds to the initiating
entity's "session" with the receiving entity. The start of the XML entity's "session" with the receiving entity. The start of the
stream is denoted unambiguously by an opening XML <stream> tag XML stream is denoted unambiguously by an opening XML <stream> tag
(with appropriate attributes and namespace declarations), while (with appropriate attributes and namespace declarations), while
the end of the XML stream is denoted unambiguously by a closing the end of the XML stream is denoted unambiguously by a closing
XML </stream> tag. An XML stream is unidirectional; in order to XML </stream> tag. An XML stream is unidirectional; in order to
enable bidirectional information exchange, the initiating entity enable bidirectional information exchange, the initiating entity
and receiving entity MUST negotiate one stream in each direction and receiving entity MUST negotiate one stream in each direction
(the "initial stream" and the "response stream"), normally over (the "initial stream" and the "response stream"), normally over
the same TCP connection. the same TCP connection.
Definition of XML Stanza: An XML stanza is a discrete semantic unit Definition of XML Stanza: An XML stanza is a discrete semantic unit
of structured information that is sent from one entity to another of structured information that is sent from one entity to another
over an XML stream. An XML stanza exists at the direct child 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
it matches production [43] content of the XML specification [1]). well-balanced if it matches production [43] content of [XML]).
The start of any XML stanza is denoted unambiguously by the The start of any XML stanza is denoted unambiguously by the
element start tag at depth=1 of the XML stream (e.g., <presence>), element start tag at depth=1 of the XML stream (e.g., <presence>),
and the end of any XML stanza is denoted unambiguously by the and the end of any XML stanza is denoted unambiguously by the
corresponding close tag at depth=1 (e.g., </presence>). An XML corresponding close tag at depth=1 (e.g., </presence>). An XML
stanza MAY contain child elements (with accompanying attributes, stanza MAY contain child elements (with accompanying attributes,
elements, and CDATA) as necessary in order to convey the desired elements, and CDATA) as necessary in order to convey the desired
information. The only defined XML stanzas are <message/>, information. The only defined XML stanzas are <message/>,
<presence/>, and <iq/> as defined under XML Stanzas (Section 9); <presence/>, and <iq/> as defined under XML Stanzas (Section 9);
an XML element sent for the purpose of stream encryption (Section an XML element sent for the purpose of Transport Layer Security
5), stream authentication (Section 6), or server dialback (Section (TLS) negotiation (Section 5), Simple Authentication and Security
Layer (SASL) negotiation (Section 6), or server dialback (Section
8) is not considered to be an XML stanza. 8) is not considered to be an XML stanza.
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 and the character encoding a text declaration specifying the XML version and the character
supported (see Inclusion of Text Declaration (Section 10.4); see also encoding supported (see Inclusion of Text Declaration (Section 11.4);
Character Encoding (Section 10.5)). Subject to local policies and see also Character Encoding (Section 11.5)). Subject to local
service provisioning, the server SHOULD then reply with a second XML policies and service provisioning, the server SHOULD then reply with
stream back to the client, again optionally preceded by a text a second XML stream back to the client, again optionally preceded by
declaration. Once the client has completed Stream Authentication a text declaration. Once the client has completed SASL negotiation
(Section 6), the client MAY send an unbounded number of XML stanzas (Section 6), the client MAY send an unbounded number of XML stanzas
over the stream to any recipient on the network. When the client over the stream to any recipient on the network. When the client
desires to close the stream, it simply sends a closing </stream> tag desires to close the stream, it simply sends a closing </stream> tag
to the server (alternatively, the stream may be closed by the to the server (alternatively, the stream may be closed by the
server), after which both the client and server SHOULD close the server), after which both the client and server SHOULD close the
underlying TCP connection as well. underlying TCP connection as well.
Those who are accustomed to thinking of XML in a document-centric Those who are accustomed to thinking of XML in a document-centric
manner may wish to view a client's session with a server as manner may wish to view a client's session with a server as
consisting of two open-ended XML documents: one from the client to consisting of two open-ended XML documents: one from the client to
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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
header from the initiating entity to the receiving entity, and header from the initiating entity to the receiving entity, and
MUST be set to the JID of the receiving entity. There SHOULD be no MUST be set to a hostname serviced by the receiving entity. There
'to' attribute set in the XML stream header 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 silently ignored by the a 'to' attribute is included, it SHOULD be silently ignored by the
initiating 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
header from the receiving entity to the initiating entity, and header from the receiving entity to the initiating entity, and
MUST be set to the JID of the receiving entity granting access to MUST be set to a hostname serviced by the receiving entity that is
the initiating entity. There SHOULD be no 'from' attribute on the granting access to the initiating entity. There SHOULD be no
XML stream header sent from the initiating entity to the receiving 'from' attribute on the XML stream header sent from the initiating
entity; however, if a 'from' attribute is included, it SHOULD be entity to the receiving entity; however, if a 'from' attribute is
silently 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
header from the receiving entity to the initiating entity. This header from the receiving entity to the initiating entity. This
attribute is a unique identifier created by the receiving entity attribute is a unique identifier created by the receiving entity
to function as a session key for the initiating entity's streams to function as a session key for the initiating entity's streams
with the receiving entity, and MUST be unique within the receiving with the receiving entity, and MUST be unique within the receiving
application (normally a server). There SHOULD be no 'id' attribute application (normally a server). There SHOULD be no 'id'
on the XML stream header sent from the initiating entity to the attribute on the XML stream header sent from the initiating entity
receiving entity; however, if an 'id' attribute is included, it to the receiving entity; however, if an 'id' attribute is
SHOULD be silently ignored by the receiving entity. included, it SHOULD be silently ignored by the receiving entity.
o xml:lang -- An 'xml:lang' attribute (as defined in Section 2.12 of o xml:lang -- An 'xml:lang' attribute (as defined in Section 2.12 of
the XML specification [1]) SHOULD be included by the initiating [XML]) SHOULD be included by the initiating entity on the header
entity on the header for the initial stream to specify the default for the initial stream to specify the default language of any
language of any human-readable XML character data it sends over human-readable XML character data it sends over that stream. If
that stream. If included, the receiving entity SHOULD remember the attribute is included, the receiving entity SHOULD remember
that value as the default for both the initial stream and the that value as the default for both the initial stream and the
response stream; if not included, the receiving entity SHOULD use response stream; if the attribute is not included, the receiving
a configurable default value for both streams, which it MUST entity SHOULD use a configurable default value for both streams,
communicate in the header for the response stream. For all stanzas which it MUST communicate in the header for the response stream.
sent over the initial stream, if the initiating entity does not For all stanzas sent over the initial stream, if the initiating
include an 'xml:lang' attribute, the receiving entity SHOULD apply entity does not include an 'xml:lang' attribute, the receiving
the default value; if the initiating entity does include an entity SHOULD apply the default value; if the initiating entity
'xml:lang' attribute, the receiving entity MUST NOT modify or does include an 'xml:lang' attribute, the receiving entity MUST
delete it (see also xml:lang (Section 9.1.5)). The value of the NOT modify or delete it (see also xml:lang (Section 9.1.5)). The
'xml:lang' attribute MUST be an NMTOKEN and MUST conform to the value of the 'xml:lang' attribute MUST be an NMTOKEN (as defined
format defined in RFC 3066 [16]. in Section 2.3 of [XML]) and MUST conform to the format defined in
RFC 3066 [LANGTAGS].
o version -- The presence of the version attribute set to a value of o version -- The presence of the version attribute set to a value of
"1.0" signals support for the stream-related protocols (including "1.0" signals support for the stream-related protocols (including
stream features) defined in this specification. Detailed rules stream features) defined in this specification. Detailed rules
regarding generation and handling of this attribute are defined regarding generation and handling of this attribute are defined
below. below.
We can summarize as follows: We can summarize as follows:
| initiating to receiving | receiving to initiating | initiating to receiving | receiving to initiating
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from | silently ignored | hostname of receiver from | silently ignored | hostname of receiver
id | silently ignored | session key id | silently ignored | session key
xml:lang | default language | default language xml:lang | default language | default language
version | signals XMPP 1.0 support | signals XMPP 1.0 support version | signals XMPP 1.0 support | signals XMPP 1.0 support
4.2.1 Version Support 4.2.1 Version Support
The following rules apply to the generation and handling of the The following rules apply to the generation and handling of the
'version' attribute: 'version' attribute:
1. If the initiating entity complies with the XML streams protocol 1. If the initiating entity complies with the stream-related
defined herein (including Stream Encryption (Section 5), Stream protocols defined herein (including Use of TLS (Section 5), Use
Authentication (Section 6), and Stream Errors (Section 4.6)), it of SASL (Section 6), and Stream Errors (Section 4.6)), it MUST
MUST include the 'version' attribute in the XML stream header it include the 'version' attribute in the XML stream header it sends
sends to the receiving entity, and it MUST set the value of the to the receiving entity, and it MUST set the value of the
'version' attribute to "1.0". 'version' attribute to "1.0".
2. If the initiating entity includes the 'version' attribute set to 2. If the initiating entity includes the 'version' attribute set to
a value of "1.0" in its stream header and the receiving entity a value of "1.0" in its stream header 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 'version' attribute set to a value of "1.0" in its including the 'version' attribute set to a value of "1.0" in its
stream header response. stream header response.
3. If the initiating entity does not include the 'version' attribute 3. If the initiating entity does not include the 'version' attribute
in its stream header, the receiving entity still SHOULD include in its stream header, the receiving entity still SHOULD include
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5. If the receiving entity includes the 'version' attribute set to a 5. If the receiving entity includes the 'version' attribute set to a
value other than "1.0" in its stream header response, the value other than "1.0" in its stream header response, the
initiating entity SHOULD generate an <unsupported-version/> initiating entity SHOULD generate an <unsupported-version/>
stream error and terminate the XML stream and underlying TCP stream error and terminate the XML stream and underlying TCP
connection. connection.
4.3 Namespace Declarations 4.3 Namespace Declarations
The stream element MUST possess both a streams namespace declaration The stream element MUST possess both a streams namespace declaration
and a default namespace declaration (as "namespace declaration" is and a default namespace declaration (as "namespace declaration" is
defined in the XML namespaces specification [10]). For detailed defined in the XML namespaces specification [XML-NAMES]). For
information regarding the streams namespace and default namespace, detailed information regarding the streams namespace and default
see Namespace Names and Prefixes (Section 10.2). namespace, see Namespace Names and Prefixes (Section 11.2).
4.4 Stream Features 4.4 Stream Features
If the initiating entity includes the 'version' attribute set to a If the initiating entity includes the 'version' attribute set to a
value of "1.0" in the initial stream header, the receiving entity value of "1.0" in the initial stream header, the receiving entity
MUST send a <features/> child element (prefixed by the streams MUST send a <features/> child element (prefixed by the streams
namespace prefix) to the initiating entity in order to announce any namespace prefix) to the initiating entity in order to announce any
stream-level features that can be negotiated (or capabilities that stream-level features that can be negotiated (or capabilities that
otherwise need to be advertised). Currently this is used only for otherwise need to be advertised). Currently this is used only to
Stream Encryption (Section 5), Stream Authentication (Section 6), and advertise Use of TLS (Section 5), Use of SASL (Section 6), and
Resource Binding (Section 7) as defined herein, and for Session Resource Binding (Section 7) as defined herein, and for Session
Establishment as defined in XMPP IM [21]; however, the stream Establishment as defined in [XMPP-IM]; however, the stream features
features functionality could be used to advertise other negotiable functionality could be used to advertise other negotiable features in
features in the future. If an entity does not understand or support the future. If an entity does not understand or support some
some features, it SHOULD silently ignore them. features, it SHOULD silently ignore them.
4.5 Stream Encryption and Authentication 4.5 Stream Security
XML streams in XMPP 1.0 SHOULD be encrypted as defined under Stream When negotiating XML streams in XMPP 1.0, TLS SHOULD be used as
Encryption (Section 5) and MUST be authenticated as defined under defined under Use of TLS (Section 5) and SASL MUST be used as defined
Stream Authentication (Section 6). If the initiating entity attempts under Use of SASL (Section 6). If the initiating entity attempts to
to send an XML Stanza (Section 9) before the stream has been send an XML Stanza (Section 9) before the stream has been
authenticated, the receiving entity SHOULD return a <not-authorized/> authenticated, the receiving entity SHOULD return a <not-authorized/>
stream error to the initiating entity and then terminate both the XML stream error to the initiating entity and then terminate both the XML
stream and the underlying TCP connection. stream and the underlying TCP connection.
4.6 Stream Errors 4.6 Stream Errors
The root stream element MAY contain an <error/> child element that is The root stream element MAY contain an <error/> child element that is
prefixed by the streams namespace prefix. The error child MUST be prefixed by the streams namespace prefix. The error child MUST be
sent by a compliant entity (usually a server rather than a client) if sent by a compliant entity (usually a server rather than a client) if
it perceives that a stream-level error has occurred. it perceives that a stream-level error has occurred.
skipping to change at page 16, line 42 skipping to change at page 14, line 29
<text xmlns='urn:ietf:params:xml:ns:xmpp-streams'> <text xmlns='urn:ietf:params:xml:ns:xmpp-streams'>
OPTIONAL descriptive text OPTIONAL descriptive text
</text> </text>
[OPTIONAL application-specific condition element] [OPTIONAL application-specific condition element]
</stream:error> </stream:error>
The <error/> element: The <error/> element:
o MUST contain a child element corresponding to one of the defined o MUST contain a child element corresponding to one of the defined
stanza error conditions defined below; this element MUST be stanza error conditions defined below; this element MUST be
qualified by the 'urn:ietf:params:xml:ns:xmpp-streamstreams' qualified by the 'urn:ietf:params:xml:ns:xmpp-streams' namespace
namespace (this namespace name adheres to the format defined in
The IETF XML Registry [24])
o MAY contain a <text/> child containing CDATA that describes the o MAY contain a <text/> child containing CDATA that describes the
error in more detail; this element MUST be qualified by the error in more detail; this element MUST be qualified by the
'urn:ietf:params:xml:ns:xmpp-streams' namespace and SHOULD possess 'urn:ietf:params:xml:ns:xmpp-streams' namespace and SHOULD possess
an 'xml:lang' attribute an 'xml:lang' attribute
o MAY contain a child element for an application-specific error o MAY contain a child element for an application-specific error
condition; this element MUST be qualified by an condition; this element MUST be qualified by an
application-defined namespace, and its structure is defined by application-defined namespace, and its structure is defined by
that namespace that namespace
The <text/> element is OPTIONAL. If included, it SHOULD be used only The <text/> element is OPTIONAL. If included, it SHOULD be used only
to provide descriptive or diagnostic information that supplements the to provide descriptive or diagnostic information that supplements the
meaning of a defined condition or application-specific condition. It meaning of a defined condition or application-specific condition. It
SHOULD NOT be interpreted programmatically by an application. It SHOULD NOT be interpreted programmatically by an application. It
SHOULD NOT be used as the error message presented to a user, but MAY SHOULD NOT be used as the error message presented to a user, but MAY
skipping to change at page 17, line 31 skipping to change at page 15, line 16
o <bad-format/> -- the entity has sent XML that cannot be processed; o <bad-format/> -- the entity has sent XML that cannot be processed;
this error MAY be used rather than more specific XML-related this error MAY be used rather than more specific XML-related
errors such as <bad-namespace-prefix/>, <invalid-xml/>, errors such as <bad-namespace-prefix/>, <invalid-xml/>,
<restricted-xml/>, <unsupported-encoding/>, and <restricted-xml/>, <unsupported-encoding/>, and
<xml-not-well-formed/>, although the more specific errors are <xml-not-well-formed/>, although the more specific errors are
preferred. preferred.
o <bad-namespace-prefix/> -- the entity has sent a namespace prefix o <bad-namespace-prefix/> -- the entity has sent a namespace prefix
that is unsupported, or has sent no namespace prefix on an element that is unsupported, or has sent no namespace prefix on an element
that requires such a prefix (see XML Namespace Names and Prefixes that requires such a prefix (see XML Namespace Names and Prefixes
(Section 10.2)). (Section 11.2)).
o <conflict/> -- the server is closing the active stream for this o <conflict/> -- the server is closing the active stream for this
entity because a new stream has been initiated that conflicts with entity because a new stream has been initiated that conflicts with
the existing stream. the existing stream.
o <connection-timeout/> -- the entity has not generated any traffic o <connection-timeout/> -- the entity has not generated any traffic
over the stream for some period of time (configurable according to over the stream for some period of time (configurable according to
a local service policy). a local service policy).
o <host-gone/> -- the value of the 'to' attribute provided by the o <host-gone/> -- the value of the 'to' attribute provided by the
skipping to change at page 18, line 20 skipping to change at page 16, line 4
address does not match an authorized JID or validated domain address does not match an authorized JID or validated domain
negotiated between servers via SASL or dialback, or between a negotiated between servers via SASL or dialback, or between a
client and a server via authentication and resource authorization. client and a server via authentication and resource authorization.
o <invalid-id/> -- the stream ID or dialback ID is invalid or does o <invalid-id/> -- the stream ID or dialback ID is invalid or does
not match an ID previously provided. not match an ID previously provided.
o <invalid-namespace/> -- the streams namespace name is something o <invalid-namespace/> -- the streams namespace name is something
other than "http://etherx.jabber.org/streams" or the dialback other than "http://etherx.jabber.org/streams" or the dialback
namespace name is something other than "jabber:server:dialback" namespace name is something other than "jabber:server:dialback"
(see XML Namespace Names and Prefixes (Section 10.2)). (see XML Namespace Names and Prefixes (Section 11.2)).
o <invalid-xml/> -- the entity has sent invalid XML over the stream o <invalid-xml/> -- the entity has sent invalid XML over the stream
to a server that performs validation (see Validation (Section to a server that performs validation (see Validation (Section
10.3)). 11.3)).
o <not-authorized/> -- the entity has attempted to send data before o <not-authorized/> -- the entity has attempted to send data before
the stream has been authenticated, or otherwise is not authorized the stream has been authenticated, or otherwise is not authorized
to perform an action related to stream negotiation; the receiving to perform an action related to stream negotiation; the receiving
entity MUST NOT process the offending stanza before sending the entity MUST NOT process the offending stanza before sending the
stream error. stream error.
o <policy-violation/> -- the entity has violated some local service o <policy-violation/> -- the entity has violated some local service
policy; the server MAY choose to specify the policy in the <text/> policy; the server MAY choose to specify the policy in the <text/>
element. element.
skipping to change at page 18, line 46 skipping to change at page 16, line 30
o <remote-connection-failed/> -- the server is unable to properly o <remote-connection-failed/> -- the server is unable to properly
connect to a remote resource that is required for authentication connect to a remote resource that is required for authentication
or authorization. or authorization.
o <resource-constraint/> -- the server lacks the system resources o <resource-constraint/> -- the server lacks the system resources
necessary to service the stream. necessary to service the stream.
o <restricted-xml/> -- the entity has attempted to send restricted o <restricted-xml/> -- the entity has attempted to send restricted
XML features such as a comment, processing instruction, DTD, XML features such as a comment, processing instruction, DTD,
entity reference, or unescaped character (see Restrictions entity reference, or unescaped character (see Restrictions
(Section 10.1)). (Section 11.1)).
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; the initiating entity but is redirecting traffic to another host; the
server SHOULD specify the alternate hostname or IP address in the server SHOULD specify the alternate hostname or IP address in the
CDATA of the <see-other-host/> element. CDATA of the <see-other-host/> element.
o <system-shutdown/> -- the server is being shut down and all active o <system-shutdown/> -- the server is being shut down and all active
streams are being closed. streams are being closed.
o <undefined-condition/> -- the error condition is not one of those o <undefined-condition/> -- the error condition is not one of those
defined by the other conditions in this list; this error condition defined by the other conditions in this list; this error condition
SHOULD be used only in conjunction with an application-specific SHOULD be used only in conjunction with an application-specific
condition. condition.
o <unsupported-encoding/> -- the initiating entity has encoded the o <unsupported-encoding/> -- the initiating entity has encoded the
stream in an encoding that is not supported by the server (see stream in an encoding that is not supported by the server (see
Character Encoding (Section 10.5)). Character Encoding (Section 11.5)).
o <unsupported-stanza-type/> -- the initiating entity has sent a o <unsupported-stanza-type/> -- the initiating entity has sent a
first-level child of the stream that is not supported by the first-level child of the stream that is not supported by the
server. server.
o <unsupported-version/> -- the value of the 'version' attribute o <unsupported-version/> -- the value of the 'version' attribute
provided by the initiating entity in the stream header specifies a provided by the initiating entity in the stream header specifies a
version of XMPP that is not supported by the server; the server version of XMPP that is not supported by the server; the server
MAY specify the version(s) it supports in the <text/> element. MAY specify the version(s) it supports in the <text/> element.
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]. is not well-formed as defined by [XML].
4.6.4 Application-Specific Conditions 4.6.4 Application-Specific Conditions
As noted, an application MAY provide application-specific stream As noted, an application MAY provide application-specific stream
error information by including a properly-namespaced child in the error information by including a properly-namespaced child in the
error element. The application-specific element SHOULD supplement or error element. The application-specific element SHOULD supplement or
further qualify a defined element. Thus the <error/> element will further qualify a defined element. Thus the <error/> element will
contain two or three child elements: contain two or three child elements:
<stream:error> <stream:error>
skipping to change at page 21, line 14 skipping to change at page 18, line 46
... encryption, authentication, and resource binding ... ... encryption, authentication, and resource binding ...
C: <message xml:lang='en'> C: <message xml:lang='en'>
<body>Bad XML, no closing body tag! <body>Bad XML, no closing body tag!
</message> </message>
S: <stream:error> S: <stream:error>
<xml-not-well-formed <xml-not-well-formed
xmlns='urn:ietf:params:xml:ns:xmpp-streams'/> xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>
</stream:error> </stream:error>
S: </stream:stream> S: </stream:stream>
5. Stream Encryption 5. Use of TLS
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) [11] protocol, along with a "STARTTLS" Transport Layer Security (TLS) protocol [TLS], along with a
extension that is modelled after similar extensions for the IMAP "STARTTLS" extension that is modelled after similar extensions for
[25], POP3 [26], and ACAP [27] protocols as described in RFC 2595 the IMAP [IMAP], POP3 [POP3], and ACAP [ACAP] protocols as described
[28]. The namespace name for the STARTTLS extension is in RFC 2595 [USINGTLS]. The namespace name for the STARTTLS
'urn:ietf:params:xml:ns:xmpp-tls', which adheres to the format extension is 'urn:ietf:params:xml:ns:xmpp-tls'.
defined in The IETF XML Registry [24].
An administrator of a given domain MAY require the use of TLS for An administrator of a given domain MAY require the use of TLS for
client-to-server communications, server-to-server communications, or client-to-server communications, server-to-server communications, or
both. Clients SHOULD use TLS to secure the streams prior to both. Clients SHOULD use TLS to secure the streams prior to
attempting to complete Stream Authentication (Section 6), and servers attempting to complete SASL negotiation (Section 6), and servers
SHOULD use TLS between two domains for the purpose of securing SHOULD use TLS between two domains for the purpose of securing
server-to-server communications. server-to-server communications.
The following rules apply: The following rules apply:
1. An initiating entity that complies with this specification MUST 1. An initiating entity that complies with this specification MUST
include the 'version' attribute set to a value of "1.0" in the include the 'version' attribute set to a value of "1.0" in the
initial stream header. initial stream header.
2. If the TLS negotiation occurs between two servers, 2. If the TLS negotiation occurs between two servers,
communications MUST NOT proceed until the Domain Name System communications MUST NOT proceed until the Domain Name System
(DNS) hostnames asserted by the servers have been resolved (see (DNS) hostnames asserted by the servers have been resolved (see
Server-to-Server Communications (Section 13.3)). Server-to-Server Communications (Section 14.3)).
3. When a receiving entity that complies with this specification 3. When a receiving entity that complies with this specification
receives an initial stream header that includes the 'version' receives an initial stream header that includes the 'version'
attribute set to a value of "1.0", after sending a stream header attribute set to a value of "1.0", after sending a stream header
in reply (including the version flag) it MUST include a in reply (including the version flag) it MUST include a
<starttls/> element (qualified by the <starttls/> element (qualified by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace) along with the list 'urn:ietf:params:xml:ns:xmpp-tls' namespace) along with the list
of other stream features it supports. of other stream features it supports.
4. If the initiating entity chooses to use TLS for stream 4. If the initiating entity chooses to use TLS, TLS negotiation
encryption, TLS negotiation MUST be completed before proceeding MUST be completed before proceeding to SASL negotiation; this
to SASL negotiation; this order of negotiation is required in order of negotiation is required in order to help safeguard
order to help safeguard authentication information sent during authentication information sent during SASL negotiation, as well
SASL negotiation, as well as to make it possible to base the use as to make it possible to base the use of the SASL EXTERNAL
of the SASL EXTERNAL mechanism on a certificate provided during mechanism on a certificate provided during prior TLS
prior TLS negotiation. negotiation.
5. During TLS negotiation, an entity MUST NOT send any white space 5. During TLS negotiation, an entity MUST NOT send any white space
characters (matching production [3] content of the XML characters (matching production [3] content of [XML]) within the
specification [1]) within the root stream element as separators root stream element as separators between elements (any white
between elements (any white space characters shown in the TLS space characters shown in the TLS examples below are included
examples below are included for the sake of readability only); for the sake of readability only); this prohibition helps to
this prohibition helps to ensure proper security layer byte ensure proper security layer byte precision.
precision.
6. The receiving entity MUST consider the TLS negotiation to have 6. The receiving entity MUST consider the TLS negotiation to have
begun immediately after sending the closing ">" character of the begun immediately after sending the closing ">" character of the
<proceed/> element. The initiating entity MUST consider the TLS <proceed/> element. The initiating entity MUST consider the TLS
negotiation to have begun immediately after receiving the negotiation to have begun immediately after receiving the
closing ">" character of the <proceed/> element from the closing ">" character of the <proceed/> element from the
receiving entity. receiving entity.
7. The initiating entity MUST validate the certificate presented by 7. The initiating entity MUST validate the certificate presented by
the receiving entity; there are two cases: the receiving entity; there are two cases:
8.
Case 1 -- The initiating entity has been configured with a set Case 1 -- The initiating entity has been configured with a set
of trusted root certificates: Normal certificate validation of trusted root certificates: Normal certificate validation
processing is appropriate, and SHOULD follow the rules processing is appropriate, and SHOULD follow the rules
defined for HTTP over TLS [12]. The trusted roots may be defined for HTTP over TLS [HTTP-TLS]. The trusted roots may
either a well-known public set or a manually configured Root be either a well-known public set or a manually configured
CA (e.g., an organization's own Certificate Authority or a Root CA (e.g., an organization's own Certificate Authority or
self-signed Root CA for the service as defined under High a self-signed Root CA for the service as defined under High
Security (Section 13.1)). This case is RECOMMENDED. Security (Section 14.1)). This case is RECOMMENDED.
Case 2 -- The initiating entity has been configured with the Case 2 -- The initiating entity has been configured with the
receiving entity's self-signed service certificate: Simple receiving entity's self-signed service certificate: Simple
comparison of public keys is appropriate. This case is NOT comparison of public keys is appropriate. This case is NOT
RECOMMENDED (see High Security (Section 13.1) for details). RECOMMENDED (see High Security (Section 14.1) for details).
If the above methods fail, the certificate SHOULD be presented 9. If the above methods fail, the certificate SHOULD be presented
to a human (e.g., an end user or server administrator) for to a human (e.g., an end user or server administrator) for
approval; if presented, the receiver MUST deliver the entire approval; if presented, the receiver MUST deliver the entire
certificate chain to the human, who SHOULD be given the option certificate chain to the human, who SHOULD be given the option
to store the Root CA certificate (not the service or End Entity to store the Root CA certificate (not the service or End Entity
certificate) and to not be queried again regarding acceptance of certificate) and to not be queried again regarding acceptance of
the certificate for some reasonable period of time. the certificate for some reasonable period of time. Note well
that certificates MUST be checked against the hostname as
provided by the initiating entity (e.g., a user), not the
hostname as resolved via the Domain Name System; e.g., if a user
typed "example.com" but a DNS SRV [SRV] lookup returned
"im.example.com", the certificate MUST be checked as
"example.com".
8. If the TLS negotiation is successful, the receiving entity MUST 10. If the TLS negotiation is successful, the receiving entity MUST
discard any knowledge obtained from the initiating entity before discard any knowledge obtained in an insecure manner from the
TLS takes effect. initiating entity before TLS takes effect.
9. If the TLS negotiation is successful, the initiating entity MUST 11. If the TLS negotiation is successful, the initiating entity MUST
discard any knowledge obtained from the receiving entity before discard any knowledge obtained in an insecure manner from the
TLS takes effect. receiving entity before TLS takes effect.
10. If the TLS negotiation is successful, the receiving entity MUST 12. 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.
11. If the TLS negotiation is successful, the initiating entity MUST 13. If the TLS negotiation is successful, the initiating entity MUST
continue with SASL negotiation. continue with SASL negotiation.
12. If the TLS negotiation results in failure, the receiving entity 14. If the TLS negotiation results in failure, the receiving entity
MUST terminate both the XML stream and the underlying TCP MUST terminate both the XML stream and the underlying TCP
connection. connection.
13. See Mandatory-to-Implement Technologies (Section 13.5) regarding 15. See Mandatory-to-Implement Technologies (Section 14.6) regarding
mechanisms that MUST be supported. mechanisms that MUST be supported.
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. The 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' attribute set to a value of entity, including the 'version' attribute set to a value of
skipping to change at page 24, line 19 skipping to change at page 22, line 9
5. The receiving entity MUST reply with either a <proceed/> element 5. The receiving entity MUST reply with either a <proceed/> element
or a <failure/> element qualified by the or a <failure/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace. If the failure case 'urn:ietf:params:xml:ns:xmpp-tls' namespace. If the failure case
occurs, the receiving entity MUST terminate both the XML stream occurs, the receiving entity MUST terminate both the XML stream
and the underlying TCP connection. If the proceed case occurs, and the underlying TCP connection. If the proceed case occurs,
the entities MUST attempt to complete the TLS negotiation over the entities MUST attempt to complete the TLS negotiation over
the TCP connection and MUST NOT send any further XML data until the TCP connection and MUST NOT send any further XML data until
the TLS negotiation is complete. the TLS negotiation is complete.
6. The initiating entity and receiving entity attempt to complete a 6. The initiating entity and receiving entity attempt to complete a
TLS negotiation in accordance with RFC 2246 [11]. TLS negotiation in accordance with [TLS].
7. If the TLS negotiation is unsuccessful, the receiving entity MUST 7. If the TLS negotiation is unsuccessful, the receiving entity MUST
terminate the TCP connection (it is not necessary to send a terminate the TCP connection (it is not necessary to send a
closing </stream> tag first, since the receiving entity and closing </stream> tag first, since the receiving entity and
initiating entity MUST consider the original stream to be closed initiating entity MUST consider the original stream to be closed
upon sending or receiving the <success/> element). If the TLS upon sending or receiving the <success/> element). If the TLS
negotiation is successful, the initiating entity MUST initiate a negotiation is successful, the initiating entity MUST initiate a
new stream by sending an opening XML stream header to the new stream by sending an opening XML stream header to the
receiving entity. receiving entity.
skipping to change at page 26, line 24 skipping to change at page 24, line 15
id='c2s_234' id='c2s_234'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <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 continues with Stream Authentication (Section 6). Step 9: Client continues with SASL negotiation (Section 6).
5.4 Server-to-Server Example 5.4 Server-to-Server Example
The following example shows the data flow for two servers securing a The following example shows the data flow for two servers securing a
stream using STARTTLS (note: the alternate steps shown below are stream using STARTTLS (note: the alternate steps shown below are
provided to illustrate the protocol for failure cases; they are not provided to illustrate the protocol for failure cases; they are not
exhaustive and would not necessarily be triggered by the data sent in exhaustive and would not necessarily be triggered by the data sent in
the example). the example).
Step 1: Server1 initiates stream to Server2: Step 1: Server1 initiates stream to Server2:
skipping to change at page 28, line 14 skipping to change at page 26, line 4
from='example.com' from='example.com'
id='s2s_234' id='s2s_234'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <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 continues with SASL negotiation (Section 6).
Step 9: Server1 continues with Stream Authentication (Section 6). 6. Use of SASL
6. Stream Authentication
6.1 Overview 6.1 Overview
XMPP includes a method for authenticating a stream by means of an XMPP includes a method for authenticating a stream by means of an
XMPP-specific profile of the Simple Authentication and Security Layer XMPP-specific profile of the Simple Authentication and Security Layer
(SASL) [13]. SASL provides a generalized method for adding (SASL) protocol [SASL]. SASL provides a generalized method for
authentication support to connection-based protocols, and XMPP uses a adding authentication support to connection-based protocols, and XMPP
generic XML namespace profile for SASL that conforms to Section 4 uses a generic XML namespace profile for SASL that conforms to the
("Profiling Requirements") of RFC 2222 [13] (the namespace name that profiling requirements of [SASL].
qualifies XML elements used in stream authentication is
'urn:ietf:params:xml:ns:xmpp-sasl', which adheres to the format
defined in The IETF XML Registry [24]).
The following rules apply: The following rules apply:
1. If the SASL negotiation occurs between two servers, 1. If the SASL negotiation occurs between two servers,
communications MUST NOT proceed until the Domain Name System communications MUST NOT proceed until the Domain Name System
(DNS) hostnames asserted by the servers have been resolved (see (DNS) hostnames asserted by the servers have been resolved (see
Server-to-Server Communications (Section 13.3)). Server-to-Server Communications (Section 14.3)).
2. If the initiating entity is capable of stream authentication via 2. If the initiating entity is capable of SASL negotiation, it MUST
SASL, it MUST include the 'version' attribute set to a value of include the 'version' attribute set to a value of "1.0" in the
"1.0" in the initial stream header. initial stream header.
3. If the receiving entity is capable of stream authentication via 3. If the receiving entity is capable of SASL negotiation, it MUST
SASL, it MUST send one or more authentication mechanisms within send one or more authentication mechanisms within a <mechanisms/
a <mechanisms/> element qualified by the > element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl'
'urn:ietf:params:xml:ns:xmpp-sasl' namespace in reply to the namespace in reply to the opening stream tag received from the
opening stream tag received from the initiating entity (if the initiating entity (if the opening stream tag included the
opening stream tag included the 'version' attribute set to a 'version' attribute set to a value of "1.0").
value of "1.0").
4. During SASL negotiation, an entity MUST NOT send any white space 4. During SASL negotiation, an entity MUST NOT send any white space
characters (matching production [3] content of the XML characters (matching production [3] content of [XML]) within the
specification [1]) within the root stream element as separators root stream element as separators between elements (any white
between elements (any white space characters shown in the SASL space characters shown in the SASL examples below are included
examples below are included for the sake of readability only); for the sake of readability only); this prohibition helps to
this prohibition helps to ensure proper security layer byte ensure proper security layer byte precision.
precision.
5. Any character data contained within the XML elements used during 5. Any character data contained within the XML elements used during
SASL negotiation MUST be encoded using base64 [14]. SASL negotiation MUST be encoded using base64, where the
encoding adheres to the definition in Section 3 of RFC 3548
[BASE64].
6. If supported by the selected SASL mechanism, the initiating 6. If provision of a "simple username" is supported by the selected
entity SHOULD provide a username during SASL negotiation. The SASL mechanism (e.g., this is supported by the DIGEST-MD5 and
username-value SHOULD be the initiating entity's sending domain CRAM-MD5 mechanisms but not by the EXTERNAL and GSSAPI
in the case of server-to-server communications, and SHOULD be mechanisms), during authentication the initiating entity SHOULD
the initiating entity's registered username in the case of provide its sending domain (in the case of server-to-server
client-to-server communications. communications) or registered account name (in the case of
client-to-server communications) as the simple username.
7. If supported by the selected SASL mechanism, the initiating 7. If the initiating entity wishes to act on behalf of another
entity MAY provide an authorization identity during SASL entity and the selected SASL mechanism supports transmission of
negotiation, which SHOULD be a non-default identity for which an authorization identity, the initiating entity MUST provide an
the entity is seeking authorization to impersonate (i.e., not authorization identity during SASL negotiation. If the
the default authorization identity, which is derived from the initiating entity does not wish to act on behalf of another
authentication identity as described in RFC 2222 [13]). If entity, it MUST NOT provide an authorization identity. As
provided, the authzid-value MUST be of the form <domain> (i.e., specified in [SASL], the initiating entity MUST NOT provide an
a domain identifier only) for servers and of the form authorization identity unless the authorization identity is
<node@domain> (i.e., node identifier and domain identifier) for different from the default authorization identity derived from
clients. the authentication identity as described in [SASL]. If
provided, the value of the authorization identity MUST be of the
form <domain> (i.e., a domain identifier only) for servers and
of the form <node@domain> (i.e., node identifier and domain
identifier) for clients.
8. Upon successful SASL negotiation that involves negotiation of a 8. Upon successful SASL negotiation that involves negotiation of a
security layer, the receiving entity MUST discard any knowledge security layer, the receiving entity MUST discard any knowledge
obtained from the initiating entity which was not obtained from obtained from the initiating entity which was not obtained from
the SASL negotiation itself. the SASL negotiation itself.
9. Upon successful SASL negotiation that involves negotiation of a 9. Upon successful SASL negotiation that involves negotiation of a
security layer, the initiating entity MUST discard any knowledge security layer, the initiating entity MUST discard any knowledge
obtained from the receiving entity which was not obtained from obtained from the receiving entity which was not obtained from
the SASL negotiation itself. the SASL negotiation itself.
10. See Mandatory-to-Implement Technologies (Section 13.5) regarding 10. See Mandatory-to-Implement Technologies (Section 14.6) regarding
mechanisms that MUST be supported. mechanisms that MUST be supported.
6.2 Narrative 6.2 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 1. The initiating entity requests SASL authentication by including
the '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". the receiving entity, with the value set to "1.0".
2. After sending an XML stream header in reply, the receiving entity 2. After sending an XML stream header in reply, the receiving entity
sends a list of available SASL authentication mechanisms; each of sends a list of available SASL authentication mechanisms; each of
these is a <mechanism/> element included as a child within a these is a <mechanism/> element included as a child within a
<mechanisms/> container element qualified by the <mechanisms/> container element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace, which in turn is a 'urn:ietf:params:xml:ns:xmpp-sasl' namespace, which in turn is a
child of a <features/> element in the streams namespace. If child of a <features/> element in the streams namespace. If Use
Stream Encryption (Section 5) needs to be established before a of TLS (Section 5) needs to be established before a particular
particular authentication mechanism may be used, the receiving authentication mechanism may be used, the receiving entity MUST
entity MUST NOT provide that mechanism in the list of available NOT provide that mechanism in the list of available SASL
SASL authentication mechanisms prior to stream encryption. If the authentication mechanisms prior to TLS negotiation. If the
initiating entity presents a valid certificate during prior TLS initiating entity presents a valid certificate during prior TLS
negotiation, the receiving entity SHOULD offer the SASL EXTERNAL negotiation, the receiving entity SHOULD offer the SASL EXTERNAL
mechanism to the initiating entity during stream authentication mechanism to the initiating entity during SASL negotiation (refer
(refer to RFC 2222 [13]), although the EXTERNAL mechanism MAY be to [SASL]), although the EXTERNAL mechanism MAY be offered under
offered under other circumstances as well. other circumstances as well.
3. The initiating entity selects a mechanism by sending an <auth/> 3. The initiating entity selects a mechanism by sending an <auth/>
element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl' element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl'
namespace to the receiving entity and including an appropriate namespace to the receiving entity and including an appropriate
value for the 'mechanism' attribute; this element MAY optionally value for the 'mechanism' attribute; this element MAY contain
contain character data (in SASL terminology, the "initial character data (in SASL terminology, the "initial response") if
response") if the mechanism supports or requires it. If the the mechanism supports or requires it. If the initiating entity
initiating entity selects the EXTERNAL mechanism for selects the EXTERNAL mechanism for authentication and presented a
authentication and presented a certificate during prior TLS certificate during prior TLS negotiation, the authentication
negotiation, the authentication credentials SHOULD be taken from credentials SHOULD be taken from that certificate.
that certificate.
4. If necessary, the receiving entity challenges the initiating 4. If necessary, the receiving entity challenges the initiating
entity by sending a <challenge/> element qualified by the entity by sending a <challenge/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (which entity; this element MAY contain character data (which MUST be
MUST be computed in accordance with the definition of the SASL computed in accordance with the definition of the SASL mechanism
mechanism chosen by the initiating entity). 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 qualified by the <response/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the receiving 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the receiving
entity; this element MAY optionally contain character data (which entity; this element MAY contain character data (which MUST be
MUST be computed in accordance with the definition of the SASL computed in accordance with the definition of the SASL mechanism
mechanism chosen by the initiating entity). 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 qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl' element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl'
namespace to the receiving entity. Upon receiving an <abort/> namespace to the receiving entity. Upon receiving an <abort/>
skipping to change at page 31, line 20 skipping to change at page 29, line 10
terminate the TCP connection; this allows the initiating entity terminate the TCP connection; this allows the initiating entity
(e.g., an end-user client) to tolerate incorrectly-provided (e.g., an end-user client) to tolerate incorrectly-provided
credentials (e.g., a mistyped password) without being forced to credentials (e.g., a mistyped password) without being forced to
reconnect. reconnect.
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 qualified by the a <failure/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity (the particular cause of failure SHOULD be communicated in entity (the particular cause of failure SHOULD be communicated in
an appropriate child element of the <failure/> element as defined an appropriate child element of the <failure/> element as defined
under SASL Errors (Section 6.4)). If the failure case occurs, the under SASL Errors (Section 6.4)). If the failure case occurs,
receiving entity SHOULD allow a configurable but reasonable the receiving entity SHOULD allow a configurable but reasonable
number of retries (at least 2), after which it MUST terminate the number of retries (at least 2), after which it MUST terminate the
TCP connection; this allows the initiating entity (e.g., an TCP connection; this allows the initiating entity (e.g., an
end-user client) to tolerate incorrectly-provided credentials end-user client) to tolerate incorrectly-provided credentials
(e.g., a mistyped password) without being forced to reconnect. (e.g., a mistyped password) without being forced to reconnect.
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 qualified by the a <success/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (in entity; this element MAY contain character data (in SASL
SASL terminology, "additional data with success") if required by terminology, "additional data with success") if required by the
the chosen SASL mechanism. Upon receiving the <success/> element, chosen SASL mechanism. Upon receiving the <success/> element,
the initiating entity MUST initiate a new stream by sending an the initiating entity MUST initiate a new stream by sending an
opening XML stream header to the receiving entity (it is not opening XML stream header to the receiving entity (it is not
necessary to send a closing </stream> tag first, since the necessary to send a closing </stream> tag first, since the
receiving entity and initiating entity MUST consider the original receiving entity and initiating entity MUST consider the original
stream to be closed upon sending or receiving the <success/> stream to be closed upon sending or receiving the <success/>
element). Upon receiving the new stream header from the element). Upon receiving the new stream header from the
initiating entity, the receiving entity MUST respond by sending a initiating entity, the receiving entity MUST respond by sending a
new XML stream header to the initiating entity, along with any new XML stream header to the initiating entity, along with any
available features (but NOT including the STARTTLS feature) or an available features (but NOT including the STARTTLS feature) or an
empty <features/> element (to signify that no additional features empty <features/> element (to signify that no additional features
are available); any such additional features not defined herein are available); any such additional features not defined herein
MUST be defined by the relevant extension to XMPP. MUST be defined by the relevant extension to XMPP.
6.3 SASL Definition 6.3 SASL Definition
Section 4 of the SASL specification [13] requires that the following The profiling requirements of [SASL] require that the following
information be supplied by a protocol definition: information be supplied by a protocol definition:
service name: "xmpp" service name: "xmpp"
initiation sequence: After the initiating entity provides an opening initiation sequence: After the initiating entity provides an opening
XML stream header and the receiving entity replies in kind, the XML stream header and the receiving entity replies in kind, the
receiving entity provides a list of acceptable authentication receiving entity provides a list of acceptable authentication
methods. The initiating entity chooses one method from the list methods. The initiating entity chooses one method from the list
and sends it to the receiving entity as the value of the and sends it to the receiving entity as the value of the
'mechanism' attribute possessed by an <auth/> element, optionally 'mechanism' attribute possessed by an <auth/> element, optionally
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. Upon successful negotiation, both sides consider <abort/> element. Upon successful negotiation, both sides
the original XML stream to be closed and new stream headers are consider the original XML stream to be closed and new stream
sent by both entities. headers are sent by both entities.
security layer negotiation: The security layer takes effect security layer negotiation: The security layer takes effect
immediately after sending the closing ">" character of the immediately after sending the closing ">" character of the
<success/> element for the receiving entity, and immediately after <success/> element for the receiving entity, and immediately after
receiving the closing ">" character of the <success/> element for receiving the closing ">" character of the <success/> element for
the initiating entity. The order of layers is first TCP, then TLS, the initiating entity. The order of layers is first [TCP], then
then SASL, then XMPP. [TLS], then [SASL], then XMPP.
use of the authorization identity: The authorization identity may be use of the authorization identity: The authorization identity may be
used by xmpp to denote the <node@domain> of a client or the used by xmpp to denote the <node@domain> of a client or the
sending <domain> of a server. sending <domain> of a server.
6.4 SASL Errors 6.4 SASL Errors
The following SASL-related error conditions are defined: The following SASL-related error conditions are defined:
o <aborted/> -- The receiving entity acknowledges an <abort/> o <aborted/> -- The receiving entity acknowledges an <abort/>
element sent by the initiating entity; sent in reply to the element sent by the initiating entity; sent in reply to the
<abort/> element. <abort/> element.
o <incorrect-encoding/> -- The data provided by the initiating o <incorrect-encoding/> -- The data provided by the initiating
entity could not be processed because the base64 [14] encoding is entity could not be processed because the [BASE64] encoding is
incorrect; sent in reply to a <response/> element or an <auth/> incorrect (e.g., because the encoding does not adhere to the the
element with initial challenge data. definition in Section 3 of [BASE64]); sent in reply to a
<response/> element or an <auth/> element with initial challenge
data.
o <invalid-authzid/> -- The authzid provided by the initiating o <invalid-authzid/> -- The authzid provided by the initiating
entity is invalid, either because it is incorrectly formatted or entity is invalid, either because it is incorrectly formatted or
because the initiating entity does not have permissions to because the initiating entity does not have permissions to
authorize that ID; sent in reply to a <response/> element or an authorize that ID; sent in reply to a <response/> element or an
<auth/> element with initial challenge data. <auth/> element with initial challenge data.
o <invalid-mechanism/> -- The initiating entity did not provide a o <invalid-mechanism/> -- The initiating entity did not provide a
mechanism or requested a mechanism that is not supported by the mechanism or requested a mechanism that is not supported by the
receiving entity; sent in reply to an <auth/> element. receiving entity; sent in reply to an <auth/> element.
skipping to change at page 34, line 4 skipping to change at page 31, line 42
version='1.0'> version='1.0'>
Step 2: Server responds with a stream tag sent to client: Step 2: Server responds with a stream tag sent to 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='c2s_234' id='c2s_234'
from='example.com' from='example.com'
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='urn:ietf:params:xml:ns:xmpp-sasl'> <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: Step 4: Client selects an authentication mechanism:
<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='DIGEST-MD5'/> mechanism='DIGEST-MD5'/>
Step 5: Server sends a base64 [14]-encoded challenge to client: Step 5: Server sends a [BASE64] encoded challenge to client:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09InNvbWVyZWFsbSIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgi cmVhbG09InNvbWVyZWFsbSIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgi
LGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNzCg== LGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNzCg==
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="somerealm",nonce="OA6MG9tEQGm2hh",\ realm="somerealm",nonce="OA6MG9tEQGm2hh",\
qop="auth",charset=utf-8,algorithm=md5-sess qop="auth",charset=utf-8,algorithm=md5-sess
Step 5 (alt): Server returns error to client: Step 5 (alt): Server returns error to client:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<incorrect-encoding/> <incorrect-encoding/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 6: Client sends a base64 [14]-encoded response to the challenge: Step 6: Client sends a [BASE64] encoded response to the challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
dXNlcm5hbWU9InNvbWVub2RlIixyZWFsbT0ic29tZXJlYWxtIixub25jZT0i dXNlcm5hbWU9InNvbWVub2RlIixyZWFsbT0ic29tZXJlYWxtIixub25jZT0i
T0E2TUc5dEVRR20yaGgiLGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5jPTAw T0E2TUc5dEVRR20yaGgiLGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5jPTAw
MDAwMDAxLHFvcD1hdXRoLGRpZ2VzdC11cmk9InhtcHAvZXhhbXBsZS5jb20i MDAwMDAxLHFvcD1hdXRoLGRpZ2VzdC11cmk9InhtcHAvZXhhbXBsZS5jb20i
LHJlc3BvbnNlPWQzODhkYWQ5MGQ0YmJkNzYwYTE1MjMyMWYyMTQzYWY3LGNo LHJlc3BvbnNlPWQzODhkYWQ5MGQ0YmJkNzYwYTE1MjMyMWYyMTQzYWY3LGNo
YXJzZXQ9dXRmLTgK YXJzZXQ9dXRmLTgK
</response> </response>
The decoded response is: The decoded response is:
username="somenode",realm="somerealm",\ username="somenode",realm="somerealm",\
nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\ nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\
nc=00000001,qop=auth,digest-uri="xmpp/example.com",\ nc=00000001,qop=auth,digest-uri="xmpp/example.com",\
response=d388dad90d4bbd760a152321f2143af7,charset=utf-8 response=d388dad90d4bbd760a152321f2143af7,charset=utf-8
Step 7: Server sends another base64 [14]-encoded challenge to client: Step 7: Server sends another [BASE64] encoded challenge to client:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZAo= cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZAo=
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
rspauth=ea40f60335c427b5527b84dbabcdfffd rspauth=ea40f60335c427b5527b84dbabcdfffd
Step 7 (alt): Server returns error to client: Step 7 (alt): Server returns error to client:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism-too-weak/> <temporary-auth-failure/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 8: Client responds to the challenge: Step 8: Client responds to the challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/> <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='urn:ietf:params:xml:ns:xmpp-sasl'/> <success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
skipping to change at page 36, line 8 skipping to change at page 33, line 47
Step 11: Server responds by sending a stream header to client along Step 11: Server responds by sending a stream header to client along
with any additional features (or an empty features element): with any additional features (or an empty features element):
<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='c2s_345' id='c2s_345'
from='example.com' from='example.com'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'> <bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>
<session xmlns='urn:ietf:params:xml:ns:xmpp-session'> <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>
</stream:features> </stream:features>
6.6 Server-to-Server Example 6.6 Server-to-Server Example
The following example shows the data flow for a server authenticating The following example shows the data flow for a server authenticating
with another server using SASL, normally after successful TLS with another server using SASL, normally after successful TLS
negotiation (note: the alternate steps shown below are provided to negotiation (note: the alternate steps shown below are provided to
illustrate the protocol for failure cases; they are not exhaustive illustrate the protocol for failure cases; they are not exhaustive
and would not necessarily be triggered by the data sent in the and would not necessarily be triggered by the data sent in the
example). example).
skipping to change at page 37, line 6 skipping to change at page 34, line 46
<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: Step 4: Server1 selects an authentication mechanism:
<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='DIGEST-MD5'/> mechanism='DIGEST-MD5'/>
Step 5: Server2 sends a base64 [14]-encoded challenge to Server1: Step 5: Server2 sends a [BASE64] encoded challenge to Server1:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
dXNlcm5hbWU9InNvbWVkb21haW4iLHJlYWxtPSJzb21lcmVhbG0iLG5vbmNl dXNlcm5hbWU9InNvbWVkb21haW4iLHJlYWxtPSJzb21lcmVhbG0iLG5vbmNl
PSJPQTZNRzl0RVFHbTJoaCIscW9wPSJhdXRoIixjaGFyc2V0PXV0Zi04LGFs PSJPQTZNRzl0RVFHbTJoaCIscW9wPSJhdXRoIixjaGFyc2V0PXV0Zi04LGFs
Z29yaXRobT1tZDUtc2Vzcwo= Z29yaXRobT1tZDUtc2Vzcwo=
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
username="somedomain",realm="somerealm",\ username="somedomain",realm="somerealm",\
nonce="OA6MG9tEQGm2hh",qop="auth",\ nonce="OA6MG9tEQGm2hh",qop="auth",\
charset=utf-8,algorithm=md5-sess charset=utf-8,algorithm=md5-sess
Step 5 (alt): Server2 returns error to Server1: Step 5 (alt): Server2 returns error to Server1:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<incorrect-encoding/> <incorrect-encoding/>
skipping to change at page 37, line 27 skipping to change at page 35, line 17
nonce="OA6MG9tEQGm2hh",qop="auth",\ nonce="OA6MG9tEQGm2hh",qop="auth",\
charset=utf-8,algorithm=md5-sess charset=utf-8,algorithm=md5-sess
Step 5 (alt): Server2 returns error to Server1: Step 5 (alt): Server2 returns error to Server1:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<incorrect-encoding/> <incorrect-encoding/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 6: Server1 sends a base64 [14]-encoded response to the Step 6: Server1 sends a [BASE64] encoded response to the challenge:
challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
dXNlcm5hbWU9InNvbWVkb21haW4iLHJlYWxtPSJzb21lcmVhbG0iLG5vbmNl dXNlcm5hbWU9InNvbWVkb21haW4iLHJlYWxtPSJzb21lcmVhbG0iLG5vbmNl
PSJPQTZNRzl0RVFHbTJoaCIsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsbmM9 PSJPQTZNRzl0RVFHbTJoaCIsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsbmM9
MDAwMDAwMDEscW9wPWF1dGgsZGlnZXN0LXVyaT0ieG1wcC9leGFtcGxlLmNv MDAwMDAwMDEscW9wPWF1dGgsZGlnZXN0LXVyaT0ieG1wcC9leGFtcGxlLmNv
bSIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcs bSIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcs
Y2hhcnNldD11dGYtOAo= Y2hhcnNldD11dGYtOAo=
</response> </response>
The decoded response is: The decoded response is:
username="somedomain",realm="somerealm",\ username="somedomain",realm="somerealm",\
nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\ nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\
nc=00000001,qop=auth,digest-uri="xmpp/example.com",\ nc=00000001,qop=auth,digest-uri="xmpp/example.com",\
response=d388dad90d4bbd760a152321f2143af7,charset=utf-8 response=d388dad90d4bbd760a152321f2143af7,charset=utf-8
Step 7: Server2 sends another base64 [14]-encoded challenge to Step 7: Server2 sends another [BASE64] encoded challenge to Server1:
Server1:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZAo= cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZAo=
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
rspauth=ea40f60335c427b5527b84dbabcdfffd rspauth=ea40f60335c427b5527b84dbabcdfffd
Step 7 (alt): Server2 returns error to Server1: Step 7 (alt): Server2 returns error to Server1:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<invalid-authzid/> <invalid-authzid/>
</failure> </failure>
</stream:stream> </stream:stream>
skipping to change at page 39, line 7 skipping to change at page 36, line 44
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
from='example.com' from='example.com'
id='s2s_345' id='s2s_345'
version='1.0'> version='1.0'>
<stream:features/> <stream:features/>
7. Resource Binding 7. Resource Binding
After Stream Authentication (Section 6) with the receiving entity, After SASL negotiation (Section 6) with the receiving entity, the
the initiating entity MAY want or need to bind a specific resource to initiating entity MAY want or need to bind a specific resource to
that stream. In general this applies only to clients: in order to that stream. In general this applies only to clients: in order to
conform to the addressing format (Section 3) and stanza delivery conform to the addressing format (Section 3) and stanza delivery
rules (Section 14) specified herein, there MUST be a resource rules (Section 10) specified herein, there MUST be a resource
identifier associated with the <node@domain> of the client (which is identifier associated with the <node@domain> of the client (which is
either generated by the server or provided by the client either generated by the server or provided by the client
application); this ensures that the address for use over that stream application); this ensures that the address for use over that stream
is a "full JID" of the form <node@domain/resource>. is a "full JID" of the form <node@domain/resource>.
Upon receiving a success indication within the SASL negotiation, the Upon receiving a success indication within the SASL negotiation, the
client MUST send a new stream header to the server, to which the client MUST send a new stream header to the server, to which the
server MUST respond with a stream header as well as a list of server MUST respond with a stream header as well as a list of
available stream features. Specifically, if the server requires the available stream features. Specifically, if the server requires the
client to bind a resource to the stream after successful stream client to bind a resource to the stream after successful SASL
authentication, it MUST include an empty <bind/> element qualified by negotiation, it MUST include an empty <bind/> element qualified by
the 'urn:ietf:params:xml:ns:xmpp-bind' namespace in the stream the 'urn:ietf:params:xml:ns:xmpp-bind' namespace in the stream
features list it presents to the client upon sending the header for features list it presents to the client upon sending the header for
the response stream sent after successful stream authentication (but the response stream sent after successful SASL negotiation (but not
not before): before):
Server advertises resource binding feature to client: Server advertises resource binding feature to 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='c2s_345' id='c2s_345'
from='example.com' from='example.com'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'> <bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>
</stream:features> </stream:features>
Upon being so informed that resource binding is required, the client Upon being so informed that resource binding is required, the client
MUST bind a resource to the stream by sending to the server an IQ MUST bind a resource to the stream by sending to the server an IQ
stanza of type "set" (see IQ Semantics (Section 9.2.3)) containing stanza of type "set" (see IQ Semantics (Section 9.2.3)) containing
data qualified by the 'urn:ietf:params:xml:ns:xmpp-bind' namespace. data qualified by the 'urn:ietf:params:xml:ns:xmpp-bind' namespace.
If the client wishes to allow the server to generate the resource If the client wishes to allow the server to generate the resource
identifier on its behalf, it sends an IQ stanza of type "set" that identifier on its behalf, it sends an IQ stanza of type "set" that
contains an empty <bind/> element: contains an empty <bind/> element:
skipping to change at page 40, line 45 skipping to change at page 38, line 36
</iq> </iq>
A server is NOT REQUIRED to accept the resource identifier provided A server is NOT REQUIRED to accept the resource identifier provided
by the client, and MAY override it with a resource identifier that by the client, and MAY override it with a resource identifier that
the server generates; in this case, the server SHOULD NOT return a the server generates; in this case, the server SHOULD NOT return a
stanza error (e.g., <forbidden/>) to the client but instead SHOULD stanza error (e.g., <forbidden/>) to the client but instead SHOULD
communicate the generated resource identifier to the client in the IQ communicate the generated resource identifier to the client in the IQ
result as shown above. result as shown above.
When a client supplies a resource identifier, the following stanza When a client supplies a resource identifier, the following stanza
error conditions may occur (see Stanza Errors (Section 9.3)): error conditions are possible (see Stanza Errors (Section 9.3)):
o The provided resource identifier cannot be processed by the server o The provided resource identifier cannot be processed by the server
in accordance with Resourceprep (Appendix B). in accordance with Resourceprep (Appendix B).
o The client is not allowed to bind a resource to the stream (e.g., o The client is not allowed to bind a resource to the stream (e.g.,
because the client has reached a limit on the number of bound because the client has reached a limit on the number of bound
resources allowed). resources allowed).
o The provided resource identifier is already in use. o The provided resource identifier is already in use but the server
does not allow binding of multiple resources with the same
identifier.
The protocol for these error conditions is shown below. The protocol for these error conditions is shown below.
Resource identifier cannot be processed: Resource identifier cannot be processed:
<iq type='error' id='bind_2'> <iq type='error' id='bind_2'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'> <bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<resource>someresource</resource> <resource>someresource</resource>
</bind> </bind>
<error type='modify'> <error type='modify'>
skipping to change at page 41, line 47 skipping to change at page 39, line 40
</bind> </bind>
<error type='cancel'> <error type='cancel'>
<conflict xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> <conflict xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error> </error>
</iq> </iq>
8. Server Dialback 8. Server Dialback
8.1 Overview 8.1 Overview
The Jabber protocol from which XMPP was adapted includes a "server The Jabber protocols from which XMPP was adapted include a "server
dialback" method for protecting against domain spoofing, thus making dialback" method for protecting against domain spoofing, thus making
it more difficult to spoof XML stanzas (see Server-to-Server it more difficult to spoof XML stanzas (see Server-to-Server
Communications (Section 13.3) regarding this method's security Communications (Section 14.3) regarding this method's security
characteristics). Server dialback also makes it easier to deploy characteristics). Server dialback also makes it easier to deploy
systems in which outbound messages and inbound messages are handled systems in which outbound messages and inbound messages are handled
by different machines for the same domain. The server dialback method by different machines for the same domain. The server dialback
is made possible by the existence of the Domain Name System (DNS), method is made possible by the existence of the Domain Name System
since one server can (normally) discover the authoritative server for (DNS), since one server can (normally) discover the authoritative
a given domain. server for a given domain.
Because dialback depends on DNS, inter-domain communications MUST NOT Because dialback depends on DNS, inter-domain communications MUST NOT
proceed until the DNS hostnames asserted by the servers have been proceed until the Domain Name System (DNS) hostnames asserted by the
resolved (see Server-to-Server Communications (Section 13.3)). servers have been resolved (see Server-to-Server Communications
(Section 14.3)).
The method for generating and verifying the keys used in server The method for generating and verifying the keys used in server
dialback MUST take into account the hostnames being used, the random dialback MUST take into account the hostnames being used, the random
ID generated for the stream, and a secret known by the authoritative ID generated for the stream, and a secret known by the authoritative
server's network. server's network.
Any error that occurs during dialback negotiation MUST be considered Any error that occurs during dialback negotiation MUST be considered
a stream error, resulting in termination of the stream and of the a stream error, resulting in termination of the stream and of the
underlying TCP connection. The possible error conditions are underlying TCP connection. The possible error conditions are
specified in the protocol description below. specified in the protocol description below.
skipping to change at page 43, line 35 skipping to change at page 41, line 29
| | Authoritative | | Authoritative
| send dialback key | Server | send dialback key | Server
| ----------------------> | ------------- | ----------------------> | -------------
| | | | | |
| establish connection | | establish connection |
| ----------------------> | | ----------------------> |
| | | |
| send stream header | | send stream header |
| ----------------------> | | ----------------------> |
| | | |
| establish connection |
| <---------------------- |
| |
| send stream header | | send stream header |
| <---------------------- | | <---------------------- |
| | | |
| send dialback key | | send verify request |
| ----------------------> | | ----------------------> |
| | | |
| validate dialback key | | send verify response |
| <---------------------- | | <---------------------- |
| |
| report dialback result | | report dialback result |
| <---------------------- | | <---------------------- |
| | | |
8.3 Protocol 8.3 Protocol
The detailed protocol interaction between the servers is as follows: The detailed protocol 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:
<stream:stream <stream:stream
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
xmlns='jabber:server' xmlns='jabber:server'
xmlns:db='jabber:server:dialback'> xmlns:db='jabber:server:dialback'>
Note: the 'to' and 'from' attributes are NOT REQUIRED on the Note: The 'to' and 'from' attributes are NOT REQUIRED on the
root stream element. The inclusion of the xmlns:db namespace root stream element. The inclusion of the xmlns:db namespace
declaration with the name shown indicates to Receiving Server declaration with the name shown indicates to Receiving Server
that Originating Server supports dialback. If the namespace name that Originating Server supports dialback. If the namespace
is incorrect, then Receiving Server MUST generate an name is incorrect, then Receiving Server MUST generate an
<invalid-namespace/> stream error condition and terminate both <invalid-namespace/> stream error condition and terminate both
the XML stream and the underlying TCP connection. the XML stream and the underlying TCP connection.
3. Receiving Server SHOULD send a stream header back to Originating 3. Receiving Server SHOULD send a stream header back to Originating
Server, including a unique ID for this interaction: Server, including a unique ID for this interaction:
<stream:stream <stream:stream
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
xmlns='jabber:server' xmlns='jabber:server'
xmlns:db='jabber:server:dialback' xmlns:db='jabber:server:dialback'
id='457F9224A0...'> id='457F9224A0...'>
Note: The 'to' and 'from' attributes are NOT REQUIRED on the Note: The 'to' and 'from' attributes are NOT REQUIRED on the
root stream element. If the namespace name is incorrect, then root stream element. If the namespace name is incorrect, then
Originating Server MUST generate an <invalid-namespace/> stream Originating Server MUST generate an <invalid-namespace/> stream
error condition and terminate both the XML stream and the error condition and terminate both the XML stream and the
underlying TCP connection. Note well that Receiving Server is underlying TCP connection. Note well that Receiving Server is
NOT REQUIRED to reply and MAY silently terminate the XML stream NOT REQUIRED to reply and MAY silently terminate the XML stream
and underlying TCP connection depending on security policies in and underlying TCP connection depending on security policies in
place. place; however, if Receiving Server desires to proceed, it MUST
sent a stream header back to Originating Server.
4. Originating Server sends a dialback key to Receiving Server: 4. Originating Server sends a dialback key to Receiving Server:
<db:result <db:result
to='Receiving Server' to='Receiving Server'
from='Originating Server'> from='Originating Server'>
98AF014EDC0... 98AF014EDC0...
</db:result> </db:result>
Note: this key is not examined by Receiving Server, since
Note: This key is not examined by Receiving Server, since
Receiving Server does not keep information about Originating Receiving Server does not keep information about Originating
Server between sessions. The key generated by Originating Server Server between sessions. The key generated by Originating
MUST be based in part on the value of the ID provided by 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 Receiving Server in the previous step, and in part on a secret
shared by Originating Server and Authoritative Server. If the shared by Originating Server and Authoritative Server. If the
value of the 'to' address does not match a hostname recognized value of the 'to' address does not match a hostname recognized
by Receiving Server, then Receiving Server MUST generate a by Receiving Server, then Receiving Server MUST generate a
<host-unknown/> stream error condition and terminate both the <host-unknown/> stream error condition and terminate both the
XML stream and the underlying TCP connection. If the value of XML stream and the underlying TCP connection. If the value of
the 'from' address matches a domain with which Receiving Server the 'from' address matches a domain with which Receiving Server
already has an established connection, then Receiving Server already has an established connection, then Receiving Server
MUST maintain the existing connection until it validates whether MUST maintain the existing connection until it validates whether
the new connection is legitimate; additionally, Receiving Server the new connection is legitimate; additionally, Receiving Server
MAY choose to generate a <not-authorized/> stream error MAY choose to generate a <not-authorized/> stream error
condition for the new connection and then terminate both the XML condition for the new connection and then terminate both the XML
stream and the underlying TCP connection related to the new stream and the underlying TCP connection related to the new
request. request.
5. Receiving Server establishes a TCP connection back to the domain 5. Receiving Server establishes a TCP connection back to the domain
name asserted by Originating Server, as a result of which it name asserted by Originating Server, as a result of which it
connects to Authoritative Server. (Note: as an optimization, an connects to Authoritative Server. (Note: As an optimization, an
implementation MAY reuse an existing trusted connection here implementation MAY reuse an existing trusted connection here
rather than opening a new TCP connection.) rather than opening a new TCP connection.)
6. Receiving Server sends Authoritative Server a stream header: 6. Receiving Server sends Authoritative 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'>
Note: the 'to' and 'from' attributes are NOT REQUIRED on the Note: The 'to' and 'from' attributes are NOT REQUIRED on the
root stream element. If the namespace name is incorrect, then root stream element. If the namespace name is incorrect, then
Authoritative Server MUST generate an <invalid-namespace/> Authoritative Server MUST generate an <invalid-namespace/>
stream error condition and terminate both the XML stream and the stream error condition and terminate both the XML stream and the
underlying TCP connection. 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...'>
Note: if the namespace name is incorrect, then Receiving Server Note: If the namespace name is incorrect, then Receiving Server
MUST generate an <invalid-namespace/> stream error condition and MUST generate an <invalid-namespace/> stream error condition and
terminate both the XML stream and the underlying TCP connection terminate both the XML stream and the underlying TCP connection
between it and Authoritative Server. If a stream error occurs between it and Authoritative Server. If a stream error occurs
between Receiving Server and Authoritative Server, then between Receiving Server and Authoritative Server, then
Receiving Server MUST generate a <remote-connection-failed/> Receiving Server MUST generate a <remote-connection-failed/>
stream error condition and terminate both the XML stream and the stream error condition and terminate both the XML stream and the
underlying TCP connection between it and Originating Server. underlying TCP connection between it and Originating Server.
8. Receiving Server sends Authoritative Server a stanza requesting 8. Receiving Server sends Authoritative Server a stanza requesting
that Authoritative Server verify a key: that Authoritative Server verify a key:
<db:verify <db:verify
from='Receiving Server' from='Receiving Server'
to='Originating Server' to='Originating Server'
id='457F9224A0...'> id='457F9224A0...'>
98AF014EDC0... 98AF014EDC0...
</db:verify> </db:verify>
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 3, and the key that Originating Server sent to Receiving Step 3, and the key that Originating Server sent to Receiving
Server in Step 4. Based on this information as well as shared Server in Step 4. Based on this information as well as shared
secret information within the Authoritative Server's network, secret information within the Authoritative Server's network,
the key is verified. Any verifiable method MAY be used to the key is verified. Any verifiable method MAY be used to
generate the key. If the value of the 'to' address does not generate the key. If the value of the 'to' address does not
match a hostname recognized by Authoritative Server, then match a hostname recognized by Authoritative Server, then
Authoritative Server MUST generate a <host-unknown/> stream Authoritative Server MUST generate a <host-unknown/> stream
error condition and terminate both the XML stream and the error condition and terminate both the XML stream and the
underlying TCP connection. If the value of the 'from' address underlying TCP connection. If the value of the 'from' address
skipping to change at page 47, line 7 skipping to change at page 44, line 46
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 Note: If the ID does not match that provided by Receiving Server
in Step 3, then Receiving Server MUST generate an <invalid-id/> in Step 3, then Receiving Server MUST generate an <invalid-id/>
stream error condition and terminate both the XML stream and the stream error condition and terminate both the XML stream and the
underlying TCP connection. If the value of the 'to' address does underlying TCP connection. If the value of the 'to' address
not match a hostname recognized by Receiving Server, then does not match a hostname recognized by Receiving Server, then
Receiving Server MUST generate a <host-unknown/> stream error Receiving Server MUST generate a <host-unknown/> stream error
condition and terminate both the XML stream and the underlying condition and terminate both the XML stream and the underlying
TCP connection. If the value of the 'from' address does not TCP connection. If the value of the 'from' address does not
match the hostname represented by Originating Server when match the hostname represented by Originating Server when
opening the TCP connection (or any validated domain), then opening the TCP connection (or any validated domain), then
Receiving Server MUST generate an <invalid-from/> stream error Receiving Server MUST generate an <invalid-from/> stream error
condition and terminate both the XML stream and the underlying condition and terminate both the XML stream and the underlying
TCP connection. TCP connection. After returning the verification to Receiving
Server, Authoritative Server SHOULD terminate the stream between
them.
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. If the connection is a type='valid', or reported as invalid. If the connection is
skipping to change at page 47, line 51 skipping to change at page 45, line 43
XML stream and the underlying TCP connection. Furthermore, a server XML stream and the underlying TCP connection. Furthermore, a server
MUST verify that the 'from' attribute of stanzas received from the MUST verify that the 'from' attribute of stanzas received from the
other server includes a validated domain for the stream; if a stanza other server includes a validated domain for the stream; if a stanza
does not meet this restriction, the server that receives the stanza does not meet this restriction, the server that receives the stanza
MUST generate an <invalid-from/> stream error condition and terminate MUST generate an <invalid-from/> stream error condition and terminate
both the XML stream and the underlying TCP connection. Both of these both the XML stream and the underlying TCP connection. Both of these
checks help to prevent spoofing related to particular stanzas. checks help to prevent spoofing related to particular stanzas.
9. XML Stanzas 9. XML Stanzas
After Stream Encryption (Section 5) if desired, Stream Authentication After TLS negotiation (Section 5) if desired, SASL negotiation
(Section 6), and Resource Binding (Section 7) if necessary, XML (Section 6), and Resource Binding (Section 7) if necessary, XML
stanzas can be sent over the streams. Three kinds of XML stanza are stanzas can be sent over the streams. Three kinds of XML stanza are
defined for the 'jabber:client' and 'jabber:server' namespaces: defined for the 'jabber:client' and 'jabber:server' namespaces:
<message/>, <presence/>, and <iq/>. In addition, there are five <message/>, <presence/>, and <iq/>. In addition, there are five
common attributes for these kinds of stanza. These common attributes, common attributes for these kinds of stanza. These common
as well as the basic semantics of the three stanza kinds, are defined attributes, as well as the basic semantics of the three stanza kinds,
herein; more detailed information regarding the syntax of XML stanzas are defined herein; more detailed information regarding the syntax of
in relation to instant messaging and presence applications is XML stanzas in relation to instant messaging and presence
provided in XMPP IM [21]. applications is provided in [XMPP-IM].
9.1 Common Attributes 9.1 Common Attributes
The following five attributes are common to message, presence, and IQ The following five attributes are common to message, presence, and IQ
stanzas: stanzas:
9.1.1 to 9.1.1 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. the stanza.
skipping to change at page 49, line 4 skipping to change at page 46, line 44
The 'from' attribute specifies the JID of the sender. The 'from' attribute specifies the JID of the sender.
When a server receives an XML stanza within the context of an When a server receives an XML stanza within the context of an
authenticated stream qualified by the 'jabber:client' namespace, it authenticated stream qualified by the 'jabber:client' namespace, it
MUST do one of the following: MUST do one of the following:
1. validate that the value of the 'from' attribute provided by the 1. validate that the value of the 'from' attribute provided by the
client is that of an authorized resource for the associated client is that of an authorized resource for the associated
entity entity
2. add a 'from' address to the stanza whose value is the full JID 2. add a 'from' address to the stanza whose value is the full JID
(<node@domain/resource>) determined by the server for the (<node@domain/resource>) determined by the server for the
connected resource that generated the stanza (see Determination connected resource that generated the stanza (see Determination
of Addresses (Section 3.6)) of Addresses (Section 3.5))
If a client attempts to send an XML stanza for which the value of the If a client attempts to send an XML stanza for which the value of the
'from' attribute does not match one of the connected resources for 'from' attribute does not match one of the connected resources for
that entity, the server SHOULD return an <invalid-from/> stream error that entity, the server SHOULD return an <invalid-from/> stream error
to the client. If a client attempts to send an XML stanza over a to the client. If a client attempts to send an XML stanza over a
stream that is not yet authenticated, the server SHOULD return a stream that is not yet authenticated, the server SHOULD return a
<not-authorized/> stream error to the client. If generated, both of <not-authorized/> stream error to the client. If generated, both of
these conditions MUST result in closing of the stream and termination these conditions MUST result in closing of the stream and termination
of the underlying TCP connection; this helps to prevent a denial of of the underlying TCP connection; this helps to prevent a denial of
service attack launched from a rogue client. service attack launched from a rogue client.
In the 'jabber:server' namespace, a stanza MUST possess a 'from' In the 'jabber:server' namespace, a stanza MUST possess a 'from'
attribute; if a server receives a stanza that does not meet this attribute; if a server receives a stanza that does not meet this
restriction, it MUST generate an <improper-addressing/> stream error restriction, it MUST generate an <improper-addressing/> stream error
condition. Furthermore, the domain identifier portion of the JID condition. Furthermore, the domain identifier portion of the JID
contained in the 'from' attribute MUST match the hostname (or any contained in the 'from' attribute MUST match the hostname (or any
validated domain) of the sending server as communicated in the SASL validated domain) of the sending server as communicated in the SASL
negotiation or dialback negotiation; if a server receives a stanza negotiation or dialback negotiation; if a server receives a stanza
that does not meet this restriction, it MUST generate an that does not meet this restriction, it MUST generate an
<invalid-from/> stream error condition. Both of these conditions MUST <invalid-from/> stream error condition. Both of these conditions
result in closing of the stream and termination of the underlying TCP MUST result in closing of the stream and termination of the
connection; this helps to prevent a denial of service attack launched underlying TCP connection; this helps to prevent a denial of service
from a rogue server. attack launched from a rogue server.
9.1.3 id 9.1.3 id
The optional 'id' attribute MAY be used by a sending entity for The optional 'id' attribute MAY be used by a sending entity for
internal tracking of stanzas that it sends and receives (especially internal tracking of stanzas that it sends and receives (especially
for tracking the request-response interaction inherent in the for tracking the request-response interaction inherent in the
semantics of IQ stanzas). The value of the 'id' attribute is NOT semantics of IQ stanzas). The value of the 'id' attribute is NOT
REQUIRED to be unique either globally, within a domain, or within a REQUIRED to be unique either globally, within a domain, or within a
stream. The semantics of IQ stanzas impose additional restrictions; stream. The semantics of IQ stanzas impose additional restrictions;
see IQ Semantics (Section 9.2.3). see IQ Semantics (Section 9.2.3).
9.1.4 type 9.1.4 type
The 'type' attribute specifies detailed information about the purpose The 'type' attribute specifies detailed information about the purpose
or context of the message, presence, or IQ stanza. The particular or context of the message, presence, or IQ stanza. The particular
allowable values for the 'type' attribute vary depending on whether allowable values for the 'type' attribute vary depending on whether
the stanza is a message, presence, or IQ; the values for message and the stanza is a message, presence, or IQ; the values for message and
presence stanzas are specific to instant messaging and presence presence stanzas are specific to instant messaging and presence
applications and therefore are defined in XMPP IM [21], whereas the applications and therefore are defined in [XMPP-IM], whereas the
values for IQ stanzas specify the role of an IQ stanza in a values for IQ stanzas specify the role of an IQ stanza in a
structured request-response "conversation" and thus are defined under structured request-response "conversation" and thus are defined under
IQ Semantics (Section 9.2.3) below. The only 'type' value common to IQ Semantics (Section 9.2.3) below. The only 'type' value common to
all three stanzas is "error", for which see Stanza Errors (Section all three stanzas is "error", for which see Stanza Errors (Section
9.3). 9.3).
9.1.5 xml:lang 9.1.5 xml:lang
A stanza SHOULD possess an 'xml:lang' attribute (as defined in A stanza SHOULD possess an 'xml:lang' attribute (as defined in
Section 2.12 of the XML specification [1]) if the stanza contains XML Section 2.12 of [XML]) if the stanza contains XML character data that
character data that is intended to be presented to a human user (as is intended to be presented to a human user (as explained in RFC 2277
explained in RFC 2277 [15], "internationalization is for humans"). [CHARSET], "internationalization is for humans"). The value of the
The value of the 'xml:lang' attribute specifies the default language 'xml:lang' attribute specifies the default language of any such
of any such human-readable XML character data, which MAY be human-readable XML character data, which MAY be overridden by the
overridden by the 'xml:lang' attribute of a specific child element. 'xml:lang' attribute of a specific child element. If a stanza does
If a stanza does not possess an 'xml:lang' attribute, an not possess an 'xml:lang' attribute, an implementation MUST assume
implementation MUST assume that the default language is that that the default language is that specified for the stream as defined
specified for the stream as defined under Stream Attributes (Section under Stream Attributes (Section 4.2) above. The value of the
4.2) above. The value of the 'xml:lang' attribute MUST be an NMTOKEN 'xml:lang' attribute MUST be an NMTOKEN and MUST conform to the
and MUST conform to the format defined in RFC 3066 [16]. format defined in RFC 3066 [LANGTAGS].
9.2 Basic Semantics 9.2 Basic Semantics
9.2.1 Message Semantics 9.2.1 Message Semantics
The <message/> stanza kind can be seen as a "push" mechanism whereby The <message/> stanza kind can be seen as a "push" mechanism whereby
one entity pushes information to another entity, similar to the one entity pushes information to another entity, similar to the
communications that occur in a system such as email. All message communications that occur in a system such as email. All message
stanzas SHOULD possess a 'to' attribute that specifies the intended stanzas SHOULD possess a 'to' attribute that specifies the intended
recipient of the message; upon receiving such a stanza, a server recipient of the message; upon receiving such a stanza, a server
SHOULD route or deliver it to the intended recipient (see Server SHOULD route or deliver it to the intended recipient (see Server
Rules for Handling XML Stanzas (Section 14) for general routing and Rules for Handling XML Stanzas (Section 10) for general routing and
delivery rules related to XML stanzas). delivery rules related to XML stanzas).
9.2.2 Presence Semantics 9.2.2 Presence Semantics
The <presence/> element can be seen as a basic broadcast or The <presence/> element can be seen as a basic broadcast or
"publish-subscribe" mechanism, whereby multiple entities receive "publish-subscribe" mechanism, whereby multiple entities receive
information (in this case, presence information) about an entity to information (in this case, presence information) about an entity to
which they have subscribed. In general, a publishing entity SHOULD which they have subscribed. In general, a publishing entity SHOULD
send a presence stanza with no 'to' attribute, in which case the send a presence stanza with no 'to' attribute, in which case the
server to which the entity is connected SHOULD broadcast or multiplex server to which the entity is connected SHOULD broadcast or multiplex
that stanza to all subscribing entities. However, a publishing entity that stanza to all subscribing entities. However, a publishing
MAY also send a presence stanza with a 'to' attribute, in which case entity MAY also send a presence stanza with a 'to' attribute, in
the server SHOULD route or deliver that stanza to the intended which case the server SHOULD route or deliver that stanza to the
recipient. See Server Rules for Handling XML Stanzas (Section 14) for intended recipient. See Server Rules for Handling XML Stanzas
general routing and delivery rules related to XML stanzas, and XMPP (Section 10) for general routing and delivery rules related to XML
IM [21] for presence-specific rules in the context of an instant stanzas, and [XMPP-IM] for presence-specific rules in the context of
messaging and presence application. an instant messaging and presence application.
9.2.3 IQ Semantics 9.2.3 IQ Semantics
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 [22]. The semantics of IQ enable an entity to make a ways to [HTTP]. The semantics of IQ enable an entity to make a
request of, and receive a response from, another entity. The data request of, and receive a response from, another entity. The data
content of the request and response is defined by the namespace content of the request and response is defined by the namespace
declaration of a direct child element of the IQ element, and the declaration of a direct child element of the IQ element, and the
interaction is tracked by the requesting entity through use of the interaction is tracked by the requesting entity through use of the
'id' attribute. Thus IQ interactions follow a common pattern of 'id' attribute. Thus IQ interactions follow a common pattern of
structured data exchange such as get/result or set/result (although structured data exchange such as get/result or set/result (although
an error may be returned in reply to a request if appropriate): an error may be returned in reply to a request if appropriate):
Requesting Responding Requesting Responding
Entity Entity Entity Entity
skipping to change at page 51, line 38 skipping to change at page 49, line 30
| ------------------------> | | ------------------------> |
| | | |
| <iq type='error' id='2'> | | <iq type='error' id='2'> |
| <------------------------ | | <------------------------ |
| | | |
In order to enforce these semantics, the following rules apply: In order to enforce these semantics, the following rules apply:
1. The 'id' attribute is REQUIRED for IQ stanzas. 1. The 'id' attribute is REQUIRED for IQ stanzas.
2. The 'type' attribute is REQUIRED for IQ stanzas. The value SHOULD 2. The 'type' attribute is REQUIRED for IQ stanzas. The value MUST
be one of the following (all other values SHOULD be ignored): be one of the following:
3.
* get -- The stanza is a request for information or * get -- The stanza is a request for information or
requirements. requirements.
* set -- The stanza provides required data, sets new values, or * set -- The stanza provides required data, sets new values, or
replaces existing values. replaces existing values.
* result -- The stanza is a response to a successful get or set * result -- The stanza is a response to a successful get or set
request. request.
* error -- An error has occurred regarding processing or * error -- An error has occurred regarding processing or
delivery of a previously-sent get or set (see Stanza Errors delivery of a previously-sent get or set (see Stanza Errors
(Section 9.3)). (Section 9.3)).
3. An entity that receives an IQ request of type "get" or "set" MUST 4. An entity that receives an IQ request of type "get" or "set" MUST
reply with an IQ response of type "result" or "error" (which reply with an IQ response of type "result" or "error" (which
response MUST preserve the 'id' attribute of the request). response MUST preserve the 'id' attribute of the request).
4. An entity that receives a stanza of type "result" or "error" MUST 5. An entity that receives a stanza of type "result" or "error" MUST
NOT respond to the stanza by sending a further IQ response of NOT respond to the stanza by sending a further IQ response of
type "result" or "error"; however, as shown above, the requesting type "result" or "error"; however, as shown above, the requesting
entity MAY send another request (e.g., an IQ of type "set" in entity MAY send another request (e.g., an IQ of type "set" in
order to provide required information discovered through a get/ order to provide required information discovered through a get/
result pair). result pair).
5. An IQ stanza of type "get" or "set" MUST contain one and only one 6. An IQ stanza of type "get" or "set" MUST contain one and only one
child element (properly-namespaced as defined in XMPP IM [21]) child element (properly-namespaced as defined in [XMPP-IM]) that
that specifies the semantics of the particular request or specifies the semantics of the particular request or response.
response.
6. An IQ stanza of type "result" MUST include zero or one child 7. An IQ stanza of type "result" MUST include zero or one child
elements. elements.
7. An IQ stanza of type "error" SHOULD include the child element 8. An IQ stanza of type "error" SHOULD include the child element
contained in the associated "get" or "set" and MUST include an contained in the associated "get" or "set" and MUST include an
<error/> child; for details, see Stanza Errors (Section 9.3). <error/> child; for details, see Stanza Errors (Section 9.3).
9.3 Stanza Errors 9.3 Stanza Errors
Stanza-related errors are handled in a manner similar to stream Stanza-related errors are handled in a manner similar to stream
errors (Section 4.6). However, stanza errors are not unrecoverable, errors (Section 4.6). However, stanza errors are not unrecoverable,
as stream errors are; therefore error stanzas include hints regarding as stream errors are; therefore error stanzas include hints regarding
actions that the original sender can take in order to remedy the actions that the original sender can take in order to remedy the
error. error.
skipping to change at page 54, line 18 skipping to change at page 52, line 13
that namespace. that namespace.
The <text/> element is OPTIONAL. If included, it SHOULD be used only The <text/> element is OPTIONAL. If included, it SHOULD be used only
to provide descriptive or diagnostic information that supplements the to provide descriptive or diagnostic information that supplements the
meaning of a defined condition or application-specific condition. It meaning of a defined condition or application-specific condition. It
SHOULD NOT be interpreted programmatically by an application. It SHOULD NOT be interpreted programmatically by an application. It
SHOULD NOT be used as the error message presented to a user, but MAY SHOULD NOT be used as the error message presented to a user, but MAY
be shown in addition to the error message associated with the be shown in addition to the error message associated with the
included condition element (or elements). included condition element (or elements).
Note: the XML namespace name 'urn:ietf:params:xml:ns:xmpp-stanzas' Finally, to maintain backward compatibility, the schema (specified in
that qualifies the descriptive element adheres to the format defined [XMPP-IM]) allows the optional inclusion of a 'code' attribute on the
in The IETF XML Registry [24]. <error/&gr; element.
9.3.3 Defined Conditions 9.3.3 Defined Conditions
The following stanza-related error conditions are defined for use in The following stanza-related error conditions are defined for use in
stanza errors. stanza errors.
o <bad-request/> -- the sender has sent XML that is malformed or o <bad-request/> -- the sender has sent XML that is malformed or
that cannot be processed (e.g., an IQ stanza that includes an that cannot be processed (e.g., an IQ stanza that includes an
unrecognized value of the 'type' attribute); the associated error unrecognized value of the 'type' attribute); the associated error
type SHOULD be "modify". type SHOULD be "modify".
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o <feature-not-implemented/> -- the feature requested is not o <feature-not-implemented/> -- the feature requested is not
implemented by the recipient or server and therefore cannot be implemented by the recipient or server and therefore cannot be
processed; the associated error type SHOULD be "cancel". processed; the associated error type SHOULD be "cancel".
o <forbidden/> -- the requesting entity does not possess the o <forbidden/> -- the requesting entity does not possess the
required permissions to perform the action; the associated error required permissions to perform the action; the associated error
type SHOULD be "auth". type SHOULD be "auth".
o <gone/> -- the recipient or server can no longer be contacted at o <gone/> -- the recipient or server can no longer be contacted at
this address (the error stanza MAY contain a new address in the this address (the error stanza MAY contain a new address in the
CDATA of the <gongone/> element); the associated error type SHOULD CDATA of the <gone/> element); the associated error type SHOULD be
be "modify". "modify".
o <internal-server-error/> -- the server could not process the o <internal-server-error/> -- the server could not process the
stanza because of a misconfiguration or an otherwise-undefined stanza because of a misconfiguration or an otherwise-undefined
internal server error; the associated error type SHOULD be "wait". internal server error; the associated error type SHOULD be "wait".
o <item-not-found/> -- the addressed JID or item requested cannot be o <item-not-found/> -- the addressed JID or item requested cannot be
found; the associated error type SHOULD be "cancel". found; the associated error type SHOULD be "cancel".
o <jid-malformed/> -- the value of the 'to' attribute in the o <jid-malformed/> -- the value of the 'to' attribute in the
sender's stanza does not adhere to the syntax defined in sender's stanza does not adhere to the syntax defined in
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<undefined-condition <undefined-condition
xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<text xml:lang='en' <text xml:lang='en'
xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'> xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
Some special application diagnostic information... Some special application diagnostic information...
</text> </text>
<special-application-condition xmlns='application-ns'/> <special-application-condition xmlns='application-ns'/>
</error> </error>
</message> </message>
10. XML Usage within XMPP 10. Server Rules for Handling XML Stanzas
10.1 Restrictions Compliant server implementations MUST ensure in-order processing of
XML stanzas between any two entities.
Beyond the requirement for in-order processing, each server
implementation will contain its own "delivery tree" for handling
stanzas it receives. Such a tree determines whether a stanza needs
to be routed to another domain, processed internally, or delivered to
a resource associated with a connected node. The following rules
apply:
10.1 No 'to' Address
If the stanza possesses no 'to' attribute, the server SHOULD process
it on behalf of the entity that sent it. Because all stanzas
received from other servers MUST possess a 'to' attribute, this rule
applies only to stanzas received from a registered entity (such as a
client) that is connected to the server. If the server receives a
presence stanza with no 'to' attribute, the server SHOULD broadcast
it to the entities that are subscribed to the sending entity's
presence, if applicable (the semantics of presence broadcast for
instant messaging and presence applications are defined in
[XMPP-IM]). If the server receives an IQ stanza of type "get" or
"set" with no 'to' attribute and it understands the namespace that
qualifies the content of the stanza, it MUST either process the
stanza on behalf of sending entity (where the meaning of "process" is
determined by the semantics of the qualifying namespace) or return an
error to the sending entity.
10.2 Foreign Domain
If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute does not match one of the configured hostnames
of the server itself or a subdomain thereof, the server SHOULD route
the stanza to the foreign domain (subject to local service
provisioning and security policies regarding inter-domain
communication). There are two possible cases:
A server-to-server stream already exists between the two domains: The
sender's server routes the stanza to the authoritative server for
the foreign domain over the existing stream
There exists no server-to-server stream between the two domains: The
sender's server (1) resolves the hostname of the foreign domain
(as defined under Server-to-Server Communications (Section 14.3)),
(2) negotiates a server-to-server stream between the two domains
(as defined under Use of TLS (Section 5) and Use of SASL (Section
6)), and (3) routes the stanza to the authoritative server for the
foreign domain over the newly-established stream
If routing to the recipient's server is unsuccessful, the sender's
server MUST return an error to the sender; if the recipient's server
can be contacted but delivery by the recipient's server to the
recipient is unsuccessful, the recipient's server MUST return an
error to the sender by way of the sender's server.
10.3 Subdomain
If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute matches a subdomain of one of the configured
hostnames of the server itself, the server MUST either process the
stanza itself or route the stanza to a specialized service that is
responsible for that subdomain (if the subdomain is configured), or
return an error to the sender (if the subdomain is not configured).
10.4 Mere Domain or Specific Resource
If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute matches a configured hostname of the server
itself and the JID contained in the 'to' attribute is of the form
<domain> or <domain/resource>, the server (or a defined resource
thereof) MUST either process the stanza as appropriate for the stanza
kind or return an error stanza to the sender.
10.5 Node in Same Domain
If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute matches a configured hostname of the server
itself and the JID contained in the 'to' attribute is of the form
<node@domain> or <node@domain/resource>, the server SHOULD deliver
the stanza to the intended recipient of the stanza as represented by
the JID contained in the 'to' attribute. The following rules apply:
1. If the JID contains a resource identifier (i.e., is of the form
<node@domain/resource>) and there is an available resource that
matches the full JID, the recipient's server SHOULD deliver the
stanza to the stream or session that exactly matches the resource
identifier.
2. If the JID contains a resource identifier and there is no
available resource that matches the full JID, the recipient's
server SHOULD return to the sender a <service-unavailable/>
stanza error.
3. If the JID is of the form <node@domain> and there is at least one
available resource available for the node, the recipient's server
MUST deliver the stanza to at least one of the available
resources, according to application-specific rules (a set of
delivery rules for instant messaging and presence applications is
defined in [XMPP-IM]).
11. XML Usage within XMPP
11.1 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 structured information in close to real elements in order to exchange structured information in close to real
time. Because XMPP does not require the parsing of arbitrary and time. Because XMPP does not require the parsing of arbitrary and
complete XML documents, there is no requirement that XMPP needs to complete XML documents, there is no requirement that XMPP needs to
support the full XML specification [1]. In particular, the following support the full feature set of [XML]. In particular, the following
restrictions apply. restrictions apply.
With regard to XML generation, an XMPP implementation MUST NOT inject With regard to XML generation, an XMPP implementation MUST NOT inject
into an XML stream any of the following: into an XML stream any of the following:
o comments (as defined in Section 2.5 of the XML specification [1]) o comments (as defined in Section 2.5 of [XML])
o processing instructions (Section 2.6 therein) o processing instructions (Section 2.6 therein)
o internal or external DTD subsets (Section 2.8 therein) o internal or external DTD subsets (Section 2.8 therein)
o internal or external entity references (Section 4.2 therein) with o internal or external entity references (Section 4.2 therein) with
the exception of predefined entities (Section 4.6 therein) the exception of predefined entities (Section 4.6 therein)
o character data or attribute values containing unescaped characters o character data or attribute values containing unescaped characters
that map to the predefined entities (Section 4.6 therein); such that map to the predefined entities (Section 4.6 therein); such
characters MUST be escaped characters MUST be escaped
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.
10.2 XML Namespace Names and Prefixes 11.2 XML Namespace Names and Prefixes
XML Namespaces [10] are used within all XMPP-compliant XML to create XML Namespaces [XML-NAMES] are used within all XMPP-compliant XML to
strict boundaries of data ownership. The basic function of namespaces create 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 allowable XML to be structurally mixed namespace-aware enables any allowable XML to be structurally mixed
with any data element within XMPP. Rules for XML namespace names and with any data element within XMPP. Rules for XML namespace names and
prefixes are defined in the following subsections. prefixes are defined in the following subsections.
10.2.1 Streams Namespace 11.2.1 Streams Namespace
A streams namespace declaration is REQUIRED in all XML stream A streams namespace declaration is REQUIRED in all XML stream
headers. The name of the streams namespace MUST be 'http:// headers. The name of the streams namespace MUST be 'http://
etherx.jabber.org/streams'. The element names of the <stream/> etherx.jabber.org/streams'. The element names of the <stream/>
element and its <features/> and <error/> children MUST be qualified element and its <features/> and <error/> children MUST be qualified
by the streams namespace prefix in all instances. An implementation by the streams namespace prefix in all instances. An implementation
SHOULD generate only the 'stream:' prefix for these elements, and for SHOULD generate only the 'stream:' prefix for these elements, and for
historical reasons MAY accept only the 'stream:' prefix. historical reasons MAY accept only the 'stream:' prefix.
10.2.2 Default Namespace 11.2.2 Default Namespace
A default namespace declaration is REQUIRED and is used in all XML A default namespace declaration is REQUIRED and is used in all XML
streams in order to define the allowable first-level children of the streams in order to define the allowable first-level children of the
root stream element. This namespace declaration MUST be the same for root stream element. This namespace declaration MUST be the same for
the initial stream and the response stream so that both streams are the initial stream and the response stream so that both streams are
qualified consistently. The default namespace declaration applies to qualified consistently. The default namespace declaration applies to
the stream and all stanzas sent within a stream (unless explicitly the stream and all stanzas sent within a stream (unless explicitly
qualified by another namespace, or by the prefix of the streams qualified by another namespace, or by the prefix of the streams
namespace or the dialback namespace). namespace or the dialback namespace).
skipping to change at page 58, line 37 skipping to change at page 58, line 37
A client implementation MUST support the 'jabber:client' default A client implementation MUST support the 'jabber:client' default
namespace, and for historical reasons MAY support only that default namespace, and for historical reasons MAY support only that default
namespace. namespace.
An implementation MUST NOT generate namespace prefixes for elements An implementation MUST NOT generate namespace prefixes for elements
in the default namespace if the default namespace is 'jabber:client' in the default namespace if the default namespace is 'jabber:client'
or 'jabber:server'. An implementation SHOULD NOT generate namespace or 'jabber:server'. An implementation SHOULD NOT generate namespace
prefixes for elements qualified by content (as opposed to stream) prefixes for elements qualified by content (as opposed to stream)
namespaces other than 'jabber:client' and 'jabber:server'. namespaces other than 'jabber:client' and 'jabber:server'.
Note: the 'jabber:client' and 'jabber:server' namespaces are nearly Note: The 'jabber:client' and 'jabber:server' namespaces are nearly
identical but are used in different contexts (client-to-server identical but are used in different contexts (client-to-server
communications for 'jabber:client' and server-to-server communications for 'jabber:client' and server-to-server
communications for 'jabber:server'). The only difference between the communications for 'jabber:server'). The only difference between the
two is that the 'to' and 'from' attributes are OPTIONAL on stanzas two is that the 'to' 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 sent within 'jabber:server'. If a compliant implementation accepts a
stream that is qualified by the 'jabber:client' or 'jabber:server' stream that is qualified by the 'jabber:client' or 'jabber:server'
namespace, it MUST support the common attributes (Section 9.1) and namespace, it MUST support the common attributes (Section 9.1) and
basic semantics (Section 9.2) of all three core stanza kinds basic semantics (Section 9.2) of all three core stanza kinds
(message, presence, and IQ). (message, presence, and IQ).
10.2.3 Dialback Namespace 11.2.3 Dialback Namespace
A dialback namespace declaration is REQUIRED for all elements used in A dialback namespace declaration is REQUIRED for all elements used in
server dialback (Section 8). The name of the dialback namespace MUST server dialback (Section 8). The name of the dialback namespace MUST
be 'jabber:server:dialback'. All elements qualified by this namespace be 'jabber:server:dialback'. All elements qualified by this
MUST be prefixed. An implementation SHOULD generate only the 'db:' namespace MUST be prefixed. An implementation SHOULD generate only
prefix for such elements and MAY accept only the 'db:' prefix. the 'db:' prefix for such elements and MAY accept only the 'db:'
prefix.
10.3 Validation 11.3 Validation
Except as noted with regard to 'to' and 'from' addresses for stanzas Except as noted with regard to 'to' and 'from' addresses for stanzas
within the 'jabber:server' namespace, a server is not responsible for within the 'jabber:server' namespace, a server is not responsible for
validating the XML elements forwarded to a client or another server; validating the XML elements forwarded to a client or another server;
an implementation MAY choose to provide only validated data elements an implementation MAY choose to provide only validated data elements
but is NOT REQUIRED to do so (although an implementation MUST NOT but is NOT REQUIRED to do so (although an implementation MUST NOT
accept XML that is not well-formed). Clients SHOULD NOT rely on the accept XML that is not well-formed). Clients SHOULD NOT rely on the
ability to send data which does not conform to the schemas, and ability to send data which does not conform to the schemas, and
SHOULD ignore any non-conformant elements or attributes on the SHOULD ignore any non-conformant elements or attributes on the
incoming XML stream. Validation of XML streams and stanzas is NOT incoming XML stream. Validation of XML streams and stanzas is NOT
REQUIRED or recommended, and schemas are included herein for REQUIRED or recommended, and schemas are included herein for
descriptive purposes only. descriptive purposes only.
10.4 Inclusion of Text Declaration 11.4 Inclusion of Text Declaration
Implementations SHOULD send a text declaration before sending a Implementations SHOULD send a text declaration before sending a
stream header. Applications MUST follow the rules in the XML stream header. Applications MUST follow the rules in [XML] regarding
specification [1] regarding the circumstances under which a text the circumstances under which a text declaration is included.
declaration is included.
10.5 Character Encoding
Implementations MUST support the UTF-8 (RFC 2279 [17]) transformation
of Universal Character Set (ISO/IEC 10646-1 [18]) characters, as
required by RFC 2277 [15]. Implementations MUST NOT attempt to use
any other encoding.
11. IANA Considerations
11.1 XML Namespace Name for TLS Data
A URN sub-namespace for TLS-related data in the Extensible Messaging
and Presence Protocol (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
the Extensible Messaging and Presence Protocol (XMPP) as defined
by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
11.2 XML Namespace Name for SASL Data
A URN sub-namespace for SASL-related data in the Extensible Messaging
and Presence Protocol (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
the Extensible Messaging and Presence Protocol (XMPP) as defined
by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
11.3 XML Namespace Name for Stream Errors
A URN sub-namespace for stream-related error data in the Extensible
Messaging and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-streams
Specification: [RFCXXXX]
Description: This is the XML namespace name for stream-related error
data in the Extensible Messaging and Presence Protocol (XMPP) as
defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
11.4 XML Namespace Name for Resource Binding
A URN sub-namespace for resource binding in the Extensible Messaging
and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-bind
Specification: [RFCXXXX]
Description: This is the XML namespace name for resource binding in
the Extensible Messaging and Presence Protocol (XMPP) as defined
by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
11.5 XML Namespace Name for Stanza Errors
A URN sub-namespace for stanza-related error data in the Extensible
Messaging and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-stanzas
Specification: [RFCXXXX]
Description: This is the XML namespace name for stanza-related error
data in the Extensible Messaging and Presence Protocol (XMPP) as
defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
11.6 Nodeprep Profile of Stringprep
The Nodeprep profile of stringprep is defined under Nodeprep
(Appendix A). The IANA registers Nodeprep in the stringprep profile
registry.
Name of this profile: 11.5 Character Encoding
Nodeprep Implementations MUST support the UTF-8 (RFC 2279 [UTF-8])
transformation of Universal Character Set (ISO/IEC 10646-1 [UCS2])
characters, as required by RFC 2277 [CHARSET]. Implementations MUST
NOT attempt to use any other encoding.
RFC in which the profile is defined: 12. Core Compliance Requirements
[RFCXXXX] This section summarizes the specific aspects of the Extensible
Messaging and Presence Protocol that MUST be supported by servers and
clients in order to be considered compliant implementations, as well
as additional protocol aspects that SHOULD be supported. For
compliance purposes, we draw a distinction between core protocols
(which MUST be supported by any server or client, regardless of the
specific application) and instant messaging protocols (which MUST be
supported only by instant messaging and presence applications built
on top of the core protocols). Compliance requirements that apply to
all servers and clients are specified in this section; compliance
requirements for instant messaging servers and clients are specified
in the corresponding section of [XMPP-IM].
Indicator whether or not this is the newest version of the profile: 12.1 Servers
This is the first version of Nodeprep In addition to all defined requirements with regard to security, XML
usage, and internationalization, a server MUST support the following
core protocols in order to be considered compliant:
11.7 Resourceprep Profile of Stringprep o Application of the [NAMEPREP], Nodeprep (Appendix A), and
Resourceprep (Appendix B) profiles of [STRINGPREP] to addresses
(including ensuring that domain identifiers are internationalized
domain names as defined in [IDNA])
The Resourceprep profile of stringprep is defined under Resourceprep o XML streams (Section 4), including Use of TLS (Section 5), Use of
(Appendix B). The IANA registers Resourceprep in the stringprep SASL (Section 6), and Resource Binding (Section 7)
profile registry.
Name of this profile: o The basic semantics of the three defined stanza kinds (i.e.,
<message/>, <presence/>, and <iq/>) as specified in stanza
semantics (Section 9.2)
Resourceprep o Generation (and, where appropriate, handling) of error syntax and
semantics related to streams, TLS, SASL, and XML stanzas
RFC in which the profile is defined: In addition, a server SHOULD support the following core protocol:
[RFCXXXX] o Server dialback (Section 8)
Indicator whether or not this is the newest version of the profile: 12.2 Clients
This is the first version of Resourceprep A client MUST support the following core protocols in order to be
considered compliant:
11.8 GSSAPI Service Name o XML streams (Section 4), including Use of TLS (Section 5), Use of
SASL (Section 6), and Resource Binding (Section 7)
The IANA registers "xmpp" as a GSSAPI [19] service name, as defined o The basic semantics of the three defined stanza kinds (i.e.,
under SASL Definition (Section 6.3). <message/>, <presence/>, and <iq/>) as specified in stanza
semantics (Section 9.2)
11.9 Port Numbers o Handling (and, where appropriate, generation) of error syntax and
semantics related to streams, TLS, SASL, and XML stanzas
The IANA currently registers "jabber-client" and "jabber-server" as In addition, a client SHOULD support the following core protocols:
keywords for TCP ports 5222 and 5269 respectively. The IANA shall
change these registrations to "xmpp-client" and "xmpp-server"
respectively.
These ports SHOULD be used for client-to-server and server-to-server o Generation of addresses to which the [NAMEPREP], Nodeprep
communications respectively, but their use is NOT REQUIRED. (Appendix A), and Resourceprep (Appendix B) profiles of
[STRINGPREP] can be applied without failing
12. Internationalization Considerations 13. Internationalization Considerations
XML streams MUST be encoded in UTF-8 as specified under Character XML streams MUST be encoded in UTF-8 as specified under Character
Encoding (Section 10.5). As specified under Stream Attributes Encoding (Section 11.5). As specified under Stream Attributes
(Section 4.2), an XML stream SHOULD include an 'xml:lang' attribute (Section 4.2), an XML stream SHOULD include an 'xml:lang' attribute
that is treated as the default language for any XML character data that is treated as the default language for any XML character data
sent over the stream that is intended to be presented to a human sent over the stream that is intended to be presented to a human
user. As specified under xml:lang (Section 9.1.5), an XML stanza user. As specified under xml:lang (Section 9.1.5), an XML stanza
SHOULD include an 'xml:lang' attribute if the stanza contains XML SHOULD include an 'xml:lang' attribute if the stanza contains XML
character data that is intended to be presented to a human user. A character data that is intended to be presented to a human user. A
server SHOULD apply the default 'xml:lang' attribute to stanzas it server SHOULD apply the default 'xml:lang' attribute to stanzas it
routes or delivers on behalf of connected entities, and MUST NOT routes or delivers on behalf of connected entities, and MUST NOT
modify or delete 'xml:lang' attributes from stanzas it receives from modify or delete 'xml:lang' attributes from stanzas it receives from
other entities. other entities.
13. Security Considerations 14. Security Considerations
13.1 High Security 14.1 High Security
For the purposes of XMPP communications (client-to-server and For the purposes of XMPP communications (client-to-server and
server-to-server), the term "high security" refers to the use of server-to-server), the term "high security" refers to the use of
security technologies that provide both mutual authentication and security technologies that provide both mutual authentication and
integrity-checking; in particular, when using certificate-based integrity-checking; in particular, when using certificate-based
authentication to provide high security, a chain-of-trust SHOULD be authentication to provide high security, a chain-of-trust SHOULD be
established out-of-band, although a shared certificate authority established out-of-band, although a shared certificate authority
signing certificates could allow a previously unknown certificate to signing certificates could allow a previously unknown certificate to
establish trust in-band. establish trust in-band.
skipping to change at page 63, line 24 skipping to change at page 61, line 47
communicate with the service SHOULD be configured with the Root CA communicate with the service SHOULD be configured with the Root CA
certificate rather than the service certificate; this avoids problems certificate rather than the service certificate; this avoids problems
associated with simple comparison of service certificates. If a associated with simple comparison of service certificates. If a
self-signed service certificate is used, an entity SHOULD NOT trust self-signed service certificate is used, an entity SHOULD NOT trust
it if it is changed to another self-signed certificate or a it if it is changed to another self-signed certificate or a
certificate signed by an unrecognized authority. certificate signed by an unrecognized authority.
Implementations MUST support high security. Service provisioning Implementations MUST support high security. Service provisioning
SHOULD use high security, subject to local security policies. SHOULD use high security, subject to local security policies.
13.2 Client-to-Server Communications 14.2 Client-to-Server Communications
A compliant implementation MUST support both TLS and SASL for A compliant implementation MUST support both TLS and SASL for
connections to a server. connections to a server.
The TLS protocol for encrypting XML streams (defined under Stream The TLS protocol for encrypting XML streams (defined under Use of TLS
Encryption (Section 5)) provides a reliable mechanism for helping to (Section 5)) provides a reliable mechanism for helping to ensure the
ensure the confidentiality and data integrity of data exchanged confidentiality and data integrity of data exchanged between two
between two entities. entities.
The SASL protocol for authenticating XML streams (defined under The SASL protocol for authenticating XML streams (defined under Use
Stream Authentication (Section 6)) provides a reliable mechanism for of SASL (Section 6)) provides a reliable mechanism for validating
validating that a client connecting to a server is who it claims to that a client connecting to a server is who it claims to be.
be.
Client-to-server communications MUST NOT proceed until the DNS Client-to-server communications MUST NOT proceed until the DNS
hostname asserted by the server has been resolved. Such resolutions hostname asserted by the server has been resolved. Such resolutions
SHOULD first attempt to resolve the hostname using an SRV [20] SHOULD first attempt to resolve the hostname using an [SRV] Service
Service of "xmpp-client" and Proto of "tcp", resulting in resource of "xmpp-client" and Proto of "tcp", resulting in resource records
records such as "_xmpp-client._tcp.example.com." (the use of the such as "_xmpp-client._tcp.example.com." (the use of the string
string "xmpp-client" for the service identifier is consistent with "xmpp-client" for the service identifier is consistent with the IANA
the IANA registration). If the SRV lookup fails, the fallback is a registration). If the SRV lookup fails, the fallback is a normal
normal IPv4/IPv6 address record resolution to determine the IP IPv4/IPv6 address record resolution to determine the IP address,
address, using the "xmpp-client" port of 5222 assigned by the using the "xmpp-client" port of 5222 registered with the IANA.
Internet Assigned Numbers Authority [5].
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 to protect the original server connection required. This helps to protect the
client's server from direct attack or identification by third client's server from direct attack or identification by third
parties. parties.
13.3 Server-to-Server Communications 14.3 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-domain communications. For historical reasons, a compliant inter-domain communications. For historical reasons, a compliant
implementation SHOULD also support Server Dialback (Section 8). implementation SHOULD also support Server Dialback (Section 8).
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-to-server communications MAY be disabled by the administrator server-to-server communications MAY be disabled by the administrator
of any given deployment. If a particular domain enables inter-domain of any given deployment. If a particular domain enables inter-domain
communications, it SHOULD enable high security. communications, it SHOULD enable high security.
Administrators may want to require use of SASL for server-to-server Administrators may want to require use of SASL for server-to-server
communications in order to ensure both authentication and communications in order to ensure both authentication and
confidentiality (e.g., on an organization's private network). confidentiality (e.g., on an organization's private network).
Compliant implementations SHOULD support SASL for this purpose. Compliant implementations SHOULD support SASL for this purpose.
Inter-domain connections MUST NOT proceed until the DNS hostnames Inter-domain connections MUST NOT proceed until the DNS hostnames
asserted by the servers have been resolved. Such resolutions MUST asserted by the servers have been resolved. Such resolutions MUST
first attempt to resolve the hostname using an SRV [20] Service of first attempt to resolve the hostname using an [SRV] Service of
"xmpp-server" and Proto of "tcp", resulting in resource records such "xmpp-server" and Proto of "tcp", resulting in resource records such
as "_xmpp-server._tcp.example.com." (the use of the string as "_xmpp-server._tcp.example.com." (the use of the string
"xmpp-server" for the service identifier is consistent with the IANA "xmpp-server" for the service identifier is consistent with the IANA
registration; note well that the "xmpp-server" service identifier registration; note well that the "xmpp-server" service identifier
supersedes the earlier use of a "jabber" service identifier, since supersedes the earlier use of a "jabber" service identifier, since
the earlier usage did not conform to RFC 2782 [20]; implementations the earlier usage did not conform to [SRV]; implementations desiring
desiring to be backwards compatible should continue to look for or to be backward compatible should continue to look for or answer to
answer to the "jabber" service identifier as well). If the SRV lookup the "jabber" service identifier as well). If the SRV lookup fails,
fails, the fallback is a normal IPv4/IPv6 address record resolution the fallback is a normal IPv4/IPv6 address record resolution to
to determine the IP address, using the "xmpp-server" port of 5269 determine the IP address, using the "xmpp-server" port of 5269
assigned by the Internet Assigned Numbers Authority [5]. registered with the IANA.
Server dialback helps protect against domain spoofing, thus making it Server dialback helps protect against domain spoofing, thus making it
more difficult to spoof XML stanzas. It is not a mechanism for more difficult to spoof XML stanzas. It is not a mechanism for
authenticating, securing, or encrypting streams between servers as is authenticating, securing, or encrypting streams between servers as is
done via SASL and TLS. Furthermore, it is susceptible to DNS done via SASL and TLS. Furthermore, it is susceptible to DNS
poisoning attacks unless DNSSec [29] is used, and even if the DNS poisoning attacks unless DNSSec [DNSSEC] is used, and even if the DNS
information is accurate, dialback cannot protect from attacks where information is accurate, dialback cannot protect from attacks where
the attacker is capable of hijacking the IP address of the remote the attacker is capable of hijacking the IP address of the remote
domain. Domains requiring robust security SHOULD use TLS and SASL. If domain. Domains requiring robust security SHOULD use TLS and SASL.
SASL is used for server-to-server authentication, dialback SHOULD NOT If SASL is used for server-to-server authentication, dialback SHOULD
be used since it is unnecessary. NOT be used since it is unnecessary.
13.4 Order of Layers 14.4 Order of Layers
The order of layers in which protocols MUST be stacked is as follows: The order of layers in which protocols MUST be stacked is as follows:
1. TCP 1. TCP
2. TLS 2. TLS
3. SASL 3. SASL
4. XMPP 4. XMPP
The rationale for this order is that TCP is the base connection layer The rationale for this order is that [TCP] is the base connection
used by all of the protocols stacked on top of TCP, TLS is often layer used by all of the protocols stacked on top of TCP, [TLS] is
provided at the operating system layer, SASL is often provided at the often provided at the operating system layer, [SASL] is often
application layer, and XMPP is the application itself. provided at the application layer, and XMPP is the application
itself.
13.5 Mandatory-to-Implement Technologies 14.5 Lack of SASL Channel Binding to TLS
The SASL framework does not provide a mechanism to bind SASL
authentication to a security layer providing confidentiality and
integrity protection that was negotiated at a lower layer. This lack
of a "channel binding" prevents SASL from being able to verify that
the source and destination end points to which the lower layer's
security is bound are equivalent to the end points that SASL is
authenticating. If the end points are not identical, the lower
layer's security cannot be trusted to protect data transmitted
between the SASL authenticated entities. In such a situation, a SASL
security layer should be negotiated which effectively ignores the
presence of the lower layer security.
14.6 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 plus SASL EXTERNAL(using the for both: TLS plus SASL EXTERNAL(using the
TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher supporting client-side TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher supporting client-side
certificates) certificates)
13.6 Firewalls 14.7 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 [5] (see IANA Considerations (Section 11)). registered with the IANA (see IANA Considerations (Section 15)). Use
Use of these well-known ports allows administrators to easily enable of these well-known ports allows administrators to easily enable or
or disable XMPP activity through existing and commonly-deployed disable XMPP activity through existing and commonly-deployed
firewalls. firewalls.
13.7 Use of base64 in SASL 14.8 Use of base64 in SASL
Both the client and the server SHOULD verify any base64 [14] data Both the client and the server MUST verify any [BASE64] data received
received during SASL negotiation. An implementation MUST reject (not during SASL negotiation. An implementation MUST reject (not ignore)
ignore) any characters that are not explicitly allowed by the base64 any characters that are not explicitly allowed by the base64
alphabet; this helps to guard against creation of a covert channel alphabet; this helps to guard against creation of a covert channel
that could be used to "leak" information. An implementation MUST NOT that could be used to "leak" information. An implementation MUST NOT
break on invalid input and MUST reject any sequence of base64 break on invalid input and MUST reject any sequence of base64
characters containing the pad ('=') character if that character is characters containing the pad ('=') character if that character is
included as something other than the last character of the data (e.g. included as something other than the last character of the data (e.g.
"=AAA" or "BBBB=CCC"); this helps to guard against buffer overflow "=AAA" or "BBBB=CCC"); this helps to guard against buffer overflow
attacks and other attacks on the implementation. Base encoding attacks and other attacks on the implementation. Base encoding
visually hides otherwise easily recognized information, such as visually hides otherwise easily recognized information, such as
passwords, but does not provide any computational confidentiality. passwords, but does not provide any computational confidentiality.
Base 64 encoding MUST follow the definition in Section 3 of RFC 3548 Base 64 encoding MUST follow the definition in Section 3 of RFC 3548
[14]. [BASE64].
13.8 Stringprep Profiles 14.9 Stringprep Profiles
XMPP makes use of the Nameprep [6] profile of stringprep [7] for XMPP makes use of the [NAMEPREP] profile of [STRINGPREP] for
processing of domain identifiers; for security considerations related processing of domain identifiers; for security considerations related
to Nameprep, refer to the appropriate section of RFC 3491. to Nameprep, refer to the appropriate section of [NAMEPREP].
In addition, XMPP defines two profiles of stringprep [7]: Nodeprep In addition, XMPP defines two profiles of [STRINGPREP]: Nodeprep
(Appendix A) for node identifiers and Resourceprep (Appendix B) for (Appendix A) for node identifiers and Resourceprep (Appendix B) for
resource identifiers. resource identifiers.
The Unicode and ISO/IEC 10646 repertoires have many characters that The Unicode and ISO/IEC 10646 repertoires have many characters that
look similar. In many cases, users of security protocols might do look similar. In many cases, users of security protocols might do
visual matching, such as when comparing the names of trusted third visual matching, such as when comparing the names of trusted third
parties. Because it is impossible to map similar-looking characters parties. Because it is impossible to map similar-looking characters
without a great deal of context such as knowing the fonts used, without a great deal of context such as knowing the fonts used,
stringprep does nothing to map similar-looking characters together stringprep does nothing to map similar-looking characters together
nor to prohibit some characters because they look like others. nor to prohibit some characters because they look like others.
skipping to change at page 66, line 47 skipping to change at page 65, line 33
on different interpretations of the internationalized node on different interpretations of the internationalized node
identifier; for example, a user entering a single internationalized identifier; for example, a user entering a single internationalized
node identifier could access another user's account information, or a node identifier could access another user's account information, or a
user could gain access to an otherwise restricted chat room or user could gain access to an otherwise restricted chat room or
service. service.
A resource identifier can be employed as one part of an entity's A resource identifier can be employed as one part of an entity's
address in XMPP. One common usage is as the name for an instant address in XMPP. One common usage is as the name for an instant
messaging user's active session; another is as the nickname of a user messaging user's active session; another is as the nickname of a user
in a multi-user chat room; and many other kinds of entities could use in a multi-user chat room; and many other kinds of entities could use
resource identifiers as part of their addresses. The security of such resource identifiers as part of their addresses. The security of
services could be compromised based on different interpretations of such services could be compromised based on different interpretations
the internationalized resource identifier; for example, a user could of the internationalized resource identifier; for example, a user
attempt to initiate multiple sessions with the same name, or a user could attempt to initiate multiple sessions with the same name, or a
could send a message to someone other than the intended recipient in user could send a message to someone other than the intended
a multi-user chat room. recipient in a multi-user chat room.
14. Server Rules for Handling XML Stanzas 15. IANA Considerations
Each server implementation will contain its own "delivery tree" for 15.1 XML Namespace Name for TLS Data
handling stanzas it receives. Such a tree determines whether a stanza
needs to be routed to another domain, processed internally, or
delivered to a resource associated with a connected node. The
following rules apply:
14.1 No 'to' Address A URN sub-namespace for TLS-related data in the Extensible Messaging
and Presence Protocol (XMPP) is defined as follows. (This namespace
name adheres to the format defined in The IETF XML Registry
[XML-REG].)
URI: urn:ietf:params:xml:ns:xmpp-tls
If the stanza possesses no 'to' attribute, the server SHOULD process Specification: XXXX
it on behalf of the entity that sent it. Because all stanzas received
from other servers MUST possess a 'to' attribute, this rule applies
only to stanzas received from a registered entity (such as a client)
that is connected to the server. If the server receives a presence
stanza with no 'to' attribute, the server SHOULD broadcast it to the
entities that are subscribed to the sending entity's presence, if
applicable (the semantics of presence broadcast for instant messaging
and presence applications are defined in XMPP IM [21]). If the server
receives an IQ stanza of type "get" or "set" with no 'to' attribute
and it understands the namespace that qualifies the content of the
stanza, it MUST either process the stanza on behalf of sending entity
(where the meaning of "process" is determined by the semantics of the
qualifying namespace) or return an error to the sending entity.
14.2 Foreign Domain Description: This is the XML namespace name for TLS-related data in
the Extensible Messaging and Presence Protocol (XMPP) as defined
by XXXX.
If the hostname of the domain identifier portion of the JID contained Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
in the 'to' attribute does not match one of the configured hostnames
of the server itself or a subdomain thereof, the server SHOULD route
the stanza to the foreign domain (subject to local service
provisioning and security policies regarding inter-domain
communication). There are two possible cases:
A server-to-server stream already exists between the two domains: The 15.2 XML Namespace Name for SASL Data
sender's server routes the stanza to the authoritative server for
the foreign domain over the existing stream
There exists no server-to-server stream between the two domains: The A URN sub-namespace for SASL-related data in the Extensible Messaging
sender's server (1) resolves the hostname of the foreign domain and Presence Protocol (XMPP) is defined as follows. (This namespace
(as defined under Server-to-Server Communications (Section 13.3)), name adheres to the format defined in [XML-REG].)
(2) negotiates a server-to-server stream between the two domains
(as defined under Stream Encryption (Section 5) and Stream
Authentication (Section 6)), and (3) routes the stanza to the
authoritative server for the foreign domain over the
newly-established stream
If routing to the recipient's server is unsuccessful, the sender's
server MUST return an error to the sender; if the recipient's server
can be contacted but delivery by the recipient's server to the
recipient is unsuccessful, the recipient's server MUST return an
error to the sender by way of the sender's server.
14.3 Subdomain URI: urn:ietf:params:xml:ns:xmpp-sasl
If the hostname of the domain identifier portion of the JID contained Specification: XXXX
in the 'to' attribute matches a subdomain of one of the configured
hostnames of the server itself, the server MUST either process the
stanza itself or route the stanza to a specialized service that is
responsible for that subdomain (if the subdomain is configured), or
return an error to the sender (if the subdomain is not configured).
14.4 Mere Domain or Specific Resource Description: This is the XML namespace name for SASL-related data in
the Extensible Messaging and Presence Protocol (XMPP) as defined
by XXXX.
If the hostname of the domain identifier portion of the JID contained Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
in the 'to' attribute matches a configured hostname of the server
itself and the JID contained in the 'to' attribute is of the form
<domain> or <domain/resource>, the server (or a defined resource
thereof) MUST either process the stanza as appropriate for the stanza
kind or return an error stanza to the sender.
14.5 Node in Same Domain 15.3 XML Namespace Name for Stream Errors
If the hostname of the domain identifier portion of the JID contained A URN sub-namespace for stream-related error data in the Extensible
in the 'to' attribute matches a configured hostname of the server Messaging and Presence Protocol (XMPP) is defined as follows. (This
itself and the JID contained in the 'to' attribute is of the form namespace name adheres to the format defined in [XML-REG].)
<node@domain> or <node@domain/resource>, the server SHOULD deliver
the stanza to the intended recipient of the stanza as represented by
the JID contained in the 'to' attribute. The following rules apply:
1. If the JID contains a resource identifier (i.e., is of the form URI: urn:ietf:params:xml:ns:xmpp-streams
<node@domain/resource>) and there is an available resource that
matches the full JID, the recipient's server SHOULD deliver the
stanza to the stream or session that exactly matches the resource
identifier.
2. If the JID contains a resource identifier and there is no Specification: XXXX
available resource that matches the full JID, the recipient's
server SHOULD return to the sender a <service-unavailable/>
stanza error.
3. If the JID is of the form <node@domain> and there is at least one Description: This is the XML namespace name for stream-related error
available resource available for the node, the recipient's server data in the Extensible Messaging and Presence Protocol (XMPP) as
MUST deliver the stanza to at least one of the available defined by XXXX.
resources, according to application-specific rules (a set of
delivery rules for instant messaging and presence applications is
defined in XMPP IM [21]).
15. Compliance Requirements Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
This section summarizes the specific aspects of the Extensible 15.4 XML Namespace Name for Resource Binding
Messaging and Presence Protocol that MUST be supported by servers and
clients in order to be considered compliant implementations, as well
as additional protocol aspects that SHOULD be supported. For
compliance purposes, we draw a distinction between core protocols
(which MUST be supported by any server or client, regardless of the
specific application) and instant messaging protocols (which MUST be
supported only by instant messaging and presence applications built
on top of the core protocols). Compliance requirements that apply to
all servers and clients are specified in this section; compliance
requirements for instant messaging servers and clients are specified
in the corresponding section of XMPP IM [21].
15.1 Servers A URN sub-namespace for resource binding in the Extensible Messaging
and Presence Protocol (XMPP) is defined as follows. (This namespace
name adheres to the format defined in [XML-REG].)
In addition to all defined requirements with regard to security, XML URI: urn:ietf:params:xml:ns:xmpp-bind
usage, and internationalization, a server MUST support the following
core protocols in order to be considered compliant:
o Enforcement of the Nameprep [6], Nodeprep (Appendix A), and Specification: XXXX
Resourceprep (Appendix B) profiles of stringprep
o XML streams (Section 4), including stream encryption (Section 5) Description: This is the XML namespace name for resource binding in
using TLS, stream authentication (Section 6) using SASL, and the Extensible Messaging and Presence Protocol (XMPP) as defined
resource binding (Section 7) by XXXX.
o The basic semantics of the three defined stanza kinds (i.e., Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
<message/>, <presence/>, and <iq/>) as specified in stanza
semantics (Section 9.2)
o Generation (and, where appropriate, handling) of error syntax and 15.5 XML Namespace Name for Stanza Errors
semantics related to streams, TLS, SASL, and XML stanzas
In addition, a server SHOULD support the following core protocol: A URN sub-namespace for stanza-related error data in the Extensible
Messaging and Presence Protocol (XMPP) is defined as follows. (This
namespace name adheres to the format defined in [XML-REG].)
o Server dialback (Section 8) URI: urn:ietf:params:xml:ns:xmpp-stanzas
15.2 Clients Specification: XXXX
A client MUST support the following core protocols in order to be Description: This is the XML namespace name for stanza-related error
considered compliant: data in the Extensible Messaging and Presence Protocol (XMPP) as
defined by XXXX.
o XML streams (Section 4), including stream encryption (Section 5) Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
using TLS, stream authentication (Section 6) using SASL, and
resource binding (Section 7)
o The basic semantics of the three defined stanza kinds (i.e., 15.6 Nodeprep Profile of Stringprep
<message/>, <presence/>, and <iq/>) as specified in stanza
semantics (Section 9.2)
o Handling (and, where appropriate, generation) of error syntax and The Nodeprep profile of stringprep is defined under Nodeprep
semantics related to streams, TLS, SASL, and XML stanzas (Appendix A). The IANA registers Nodeprep in the stringprep profile
registry.
In addition, a client SHOULD support the following core protocols: Name of this profile:
o Generation of addresses in accordance with the Nameprep [6], Nodeprep
Nodeprep (Appendix A), and Resourceprep (Appendix B) profiles of
stringprep
Normative References RFC in which the profile is defined:
[1] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, XXXX
"Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC-xml,
October 2000, <http://www.w3.org/TR/REC-xml>.
[2] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging / Indicator whether or not this is the newest version of the profile:
Presence Protocol Requirements", RFC 2779, February 2000.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement This is the first version of Nodeprep
Levels", BCP 14, RFC 2119, March 1997.
[4] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, 15.7 Resourceprep Profile of Stringprep
September 1981.
[5] Internet Assigned Numbers Authority, "Internet Assigned Numbers The Resourceprep profile of stringprep is defined under Resourceprep
Authority", January 1998, <http://www.iana.org/>. (Appendix B). The IANA registers Resourceprep in the stringprep
profile registry.
[6] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile Name of this profile:
for Internationalized Domain Names (IDN)", RFC 3491, March
2003.
[7] Hoffman, P. and M. Blanchet, "Preparation of Internationalized Resourceprep
Strings ("stringprep")", RFC 3454, December 2002.
[8] Crocker, D. and P. Overell, "Augmented BNF for Syntax RFC in which the profile is defined:
Specifications: ABNF", RFC 2234, November 1997.
[9] Hinden, R. and S. Deering, "IP Version 6 Addressing XXXX
Architecture", RFC 2373, July 1998.
[10] Bray, T., Hollander, D. and A. Layman, "Namespaces in XML", W3C Indicator whether or not this is the newest version of the profile:
REC-xml-names, January 1999, <http://www.w3.org/TR/
REC-xml-names>.
[11] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and This is the first version of Resourceprep
P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January
1999.
[12] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. 15.8 GSSAPI Service Name
[13] Myers, J., "Simple Authentication and Security Layer (SASL)", The IANA registers "xmpp" as a GSSAPI [GSS-API] service name, as
RFC 2222, October 1997. defined under SASL Definition (Section 6.3).
[14] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", 15.9 Port Numbers
RFC 3548, July 2003.
[15] Alvestrand, H., "IETF Policy on Character Sets and Languages", The IANA currently registers "jabber-client" and "jabber-server" as
BCP 18, RFC 2277, January 1998. keywords for [TCP] ports 5222 and 5269 respectively. The IANA shall
change these registrations to "xmpp-client" and "xmpp-server"
respectively.
[16] Alvestrand, H., "Tags for the Identification of Languages", BCP These ports SHOULD be used for client-to-server and server-to-server
47, RFC 3066, January 2001. communications respectively, but their use is NOT REQUIRED.
[17] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC Normative References
2279, January 1998.
[18] International Organization for Standardization, "Information [ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Technology - Universal Multiple-octet coded Character Set (UCS) Specifications: ABNF", RFC 2234, November 1997.
- Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO
Standard 10646-1 Addendum 2, October 1996.
[19] Linn, J., "Generic Security Service Application Program [BASE64] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 3548, July 2003.
[CHARSET] Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, January 1998.
[GSS-API] Linn, J., "Generic Security Service Application Program
Interface, Version 2", RFC 2078, January 1997. Interface, Version 2", RFC 2078, January 1997.
[20] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for [HTTP-TLS]
Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[IMP-REQS]
Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging /
Presence Protocol Requirements", RFC 2779, February 2000.
[LANGTAGS]
Alvestrand, H., "Tags for the Identification of
Languages", BCP 47, RFC 3066, January 2001.
[IDNA] Faltstrom, P., Hoffman, P. and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[NAMEPREP]
Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
Profile for Internationalized Domain Names (IDN)", RFC
3491, March 2003.
[SASL] Myers, J., "Simple Authentication and Security Layer
(SASL)", RFC 2222, October 1997.
[SRV] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782, specifying the location of services (DNS SRV)", RFC 2782,
February 2000. February 2000.
Informative References [STRINGPREP]
Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ("STRINGPREP")", RFC 3454,
December 2002.
[21] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging", [TCP] Postel, J., "Transmission Control Protocol", STD 7, RFC
draft-ietf-xmpp-im-18 (work in progress), October 2003. 793, September 1981.
[22] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., [TERMS] Bradner, S., "Key words for use in RFCs to Indicate
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- Requirement Levels", BCP 14, RFC 2119, March 1997.
HTTP/1.1", RFC 2616, June 1999.
[23] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [TLS] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A.
Resource Identifiers (URI): Generic Syntax", RFC 2396, August and P. Kocher, "The TLS Protocol Version 1.0", RFC 2246,
1998. January 1999.
[24] Mealling, M., "The IETF XML Registry", [UCS2] International Organization for Standardization,
draft-mealling-iana-xmlns-registry-05 (work in progress), June "Information Technology - Universal Multiple-octet coded
2003. Character Set (UCS) - Amendment 2: UCS Transformation
Format 8 (UTF-8)", ISO Standard 10646-1 Addendum 2,
October 1996.
[25] Crispin, M., "Internet Message Access Protocol - Version [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO
4rev1", RFC 2060, December 1996. 10646", RFC 2279, January 1998.
[26] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD [XML] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
53, RFC 1939, May 1996. "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C
REC-xml, October 2000, <http://www.w3.org/TR/REC-xml>.
[27] Newman, C. and J. Myers, "ACAP -- Application Configuration [XML-NAMES]
Access Protocol", RFC 2244, November 1997. Bray, T., Hollander, D. and A. Layman, "Namespaces in
XML", W3C REC-xml-names, January 1999, <http://www.w3.org/
TR/REC-xml-names>.
[28] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595, Informative References
June 1999.
[29] Eastlake, D., "Domain Name System Security Extensions", RFC [ACAP] Newman, C. and J. Myers, "ACAP -- Application
2535, March 1999. Configuration Access Protocol", RFC 2244, November 1997.
[30] Jabber Software Foundation, "Jabber Software Foundation", [DNSSEC] Eastlake, D., "Domain Name System Security Extensions",
RFC 2535, March 1999.
[HTTP] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[IMAP] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 2060, December 1996.
[JSF] Jabber Software Foundation, "Jabber Software Foundation",
<http://www.jabber.org/>. <http://www.jabber.org/>.
Authors' Addresses [POP3] Myers, J. and M. Rose, "Post Office Protocol - Version 3",
STD 53, RFC 1939, May 1996.
Peter Saint-Andre [URI] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Jabber Software Foundation Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
EMail: stpeter@jabber.org [USINGTLS]
Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC
2595, June 1999.
Jeremie Miller [XML-REG] Mealling, M., "The IETF XML Registry",
draft-mealling-iana-xmlns-registry-05 (work in progress),
June 2003.
[XMPP-IM] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Instant Messaging and Presence",
draft-ietf-xmpp-im-19 (work in progress), November 2003.
Author's Address
Peter Saint-Andre
Jabber Software Foundation Jabber Software Foundation
EMail: jeremie@jabber.org EMail: stpeter@jabber.org
Appendix A. Nodeprep Appendix A. Nodeprep
A.1 Introduction A.1 Introduction
This appendix defines the "Nodeprep" profile of stringprep (RFC 3454 This appendix defines the "Nodeprep" profile of [STRINGPREP]. As
[7]). As such, it specifies processing rules that will enable users such, it specifies processing rules that will enable users to enter
to enter internationalized node identifiers in the Extensible internationalized node identifiers in the Extensible Messaging and
Messaging and Presence Protocol (XMPP) and have the highest chance of Presence Protocol (XMPP) and have the highest chance of getting the
getting the content of the strings correct. (An XMPP node identifier content of the strings correct. (An XMPP node identifier is the
is the optional portion of an XMPP address that precedes a domain optional portion of an XMPP address that precedes a domain identifier
identifier and the '@' separator; it is often but not exclusively and the '@' separator; it is often but not exclusively associated
associated with an instant messaging username.) These processing with an instant messaging username.) These processing rules are
rules are intended only for XMPP node identifiers and are not intended only for XMPP node identifiers and are not intended for
intended for arbitrary text or any other aspect of an XMPP address. arbitrary text or any other aspect of an XMPP address.
This profile defines the following, as required by RFC 3454 [7]: This profile defines the following, as required by [STRINGPREP]:
o The intended applicability of the profile: internationalized node o The intended applicability of the profile: internationalized node
identifiers within XMPP identifiers within XMPP
o The character repertoire that is the input and output to o The character repertoire that is the input and output to
stringprep: Unicode 3.2, specified in Section 2 of this Appendix stringprep: Unicode 3.2, specified in Section 2 of this Appendix
o The mappings used: specified in Section 3 o The mappings used: specified in Section 3
o The Unicode normalization used: specified in Section 4 o The Unicode normalization used: specified in Section 4
o The characters that are prohibited as output: specified in Section o The characters that are prohibited as output: specified in Section
5 5
o Bidirectional character handling: specified in Section 6 o Bidirectional character handling: specified in Section 6
A.2 Character Repertoire A.2 Character Repertoire
This profile uses Unicode 3.2 with the list of unassigned code points This profile uses Unicode 3.2 with the list of unassigned code points
being Table A.1, both defined in Appendix A of RFC 3454 [7]. being Table A.1, both defined in Appendix A of [STRINGPREP].
A.3 Mapping A.3 Mapping
This profile specifies mapping using the following tables from RFC This profile specifies mapping using the following tables from
3454 [7]: [STRINGPREP]:
Table B.1 Table B.1
Table B.2 Table B.2
A.4 Normalization A.4 Normalization
This profile specifies using Unicode normalization form KC, as This profile specifies using Unicode normalization form KC, as
described in RFC 3454 [7]. described in [STRINGPREP].
A.5 Prohibited Output A.5 Prohibited Output
This profile specifies prohibiting use of the following tables from This profile specifies prohibiting use of the following tables from
RFC 3454 [7]. [STRINGPREP].
Table C.1.1 Table C.1.1
Table C.1.2 Table C.1.2
Table C.2.1 Table C.2.1
Table C.2.2 Table C.2.2
Table C.3 Table C.3
skipping to change at page 74, line 48 skipping to change at page 73, line 24
#x3C (<) #x3C (<)
#x3E (>) #x3E (>)
#x40 (@) #x40 (@)
A.6 Bidirectional Characters A.6 Bidirectional Characters
This profile specifies checking bidirectional strings as described in This profile specifies checking bidirectional strings as described in
Section 6 of RFC 3454 [7]. Section 6 of [STRINGPREP].
Appendix B. Resourceprep Appendix B. Resourceprep
B.1 Introduction B.1 Introduction
This appendix defines the "Resourceprep" profile of stringprep (RFC This appendix defines the "Resourceprep" profile of [STRINGPREP]. As
3454 [7]). As such, it specifies processing rules that will enable such, it specifies processing rules that will enable users to enter
users to enter internationalized resource identifiers in the internationalized resource identifiers in the Extensible Messaging
Extensible Messaging and Presence Protocol (XMPP) and have the and Presence Protocol (XMPP) and have the highest chance of getting
highest chance of getting the content of the strings correct. (An the content of the strings correct. (An XMPP resource identifier is
XMPP resource identifier is the optional portion of an XMPP address the optional portion of an XMPP address that follows a domain
that follows a domain identifier and the '/' separator; it is often identifier and the '/' separator; it is often but not exclusively
but not exclusively associated with an instant messaging session associated with an instant messaging session name.) These processing
name.) These processing rules are intended only for XMPP resource rules are intended only for XMPP resource identifiers and are not
identifiers and are not intended for arbitrary text or any other intended for arbitrary text or any other aspect of an XMPP address.
aspect of an XMPP address.
This profile defines the following, as required by RFC 3454 [7]: This profile defines the following, as required by [STRINGPREP]:
o The intended applicability of the profile: internationalized o The intended applicability of the profile: internationalized
resource identifiers within XMPP resource identifiers within XMPP
o The character repertoire that is the input and output to o The character repertoire that is the input and output to
stringprep: Unicode 3.2, specified in Section 2 of this Appendix stringprep: Unicode 3.2, specified in Section 2 of this Appendix
o The mappings used: specified in Section 3 o The mappings used: specified in Section 3
o The Unicode normalization used: specified in Section 4 o The Unicode normalization used: specified in Section 4
skipping to change at page 75, line 30 skipping to change at page 74, line 4
o The intended applicability of the profile: internationalized o The intended applicability of the profile: internationalized
resource identifiers within XMPP resource identifiers within XMPP
o The character repertoire that is the input and output to o The character repertoire that is the input and output to
stringprep: Unicode 3.2, specified in Section 2 of this Appendix stringprep: Unicode 3.2, specified in Section 2 of this Appendix
o The mappings used: specified in Section 3 o The mappings used: specified in Section 3
o The Unicode normalization used: specified in Section 4 o The Unicode normalization used: specified in Section 4
o The characters that are prohibited as output: specified in Section o The characters that are prohibited as output: specified in Section
5 5
o Bidirectional character handling: specified in Section 6 o Bidirectional character handling: specified in Section 6
B.2 Character Repertoire B.2 Character Repertoire
This profile uses Unicode 3.2 with the list of unassigned code points This profile uses Unicode 3.2 with the list of unassigned code points
being Table A.1, both defined in Appendix A of RFC 3454 [7]. being Table A.1, both defined in Appendix A of [STRINGPREP].
B.3 Mapping B.3 Mapping
This profile specifies mapping using the following tables from RFC This profile specifies mapping using the following tables from
3454 [7]: [STRINGPREP]:
Table B.1 Table B.1
B.4 Normalization B.4 Normalization
This profile specifies using Unicode normalization form KC, as This profile specifies using Unicode normalization form KC, as
described in RFC 3454 [7]. described in [STRINGPREP].
B.5 Prohibited Output B.5 Prohibited Output
This profile specifies prohibiting use of the following tables from This profile specifies prohibiting use of the following tables from
RFC 3454 [7]. [STRINGPREP].
Table C.1.2 Table C.1.2
Table C.2.1 Table C.2.1
Table C.2.2 Table C.2.2
Table C.3 Table C.3
Table C.4 Table C.4
skipping to change at page 76, line 28 skipping to change at page 75, line 4
Table C.4 Table C.4
Table C.5 Table C.5
Table C.6 Table C.6
Table C.7 Table C.7
Table C.8 Table C.8
Table C.9 Table C.9
B.6 Bidirectional Characters B.6 Bidirectional Characters
This profile specifies checking bidirectional strings as described in This profile specifies checking bidirectional strings as described in
Section 6 of RFC 3454 [7]. Section 6 of [STRINGPREP].
Appendix C. XML Schemas Appendix C. XML Schemas
The following XML schemas are descriptive, not normative. For schemas The following XML schemas are descriptive, not normative. For
defining the 'jabber:client' and 'jabber:server' namespaces, refer to schemas defining the 'jabber:client' and 'jabber:server' namespaces,
XMPP IM [21]. refer to [XMPP-IM].
C.1 Streams namespace C.1 Streams 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://etherx.jabber.org/streams' targetNamespace='http://etherx.jabber.org/streams'
xmlns='http://etherx.jabber.org/streams' xmlns='http://etherx.jabber.org/streams'
elementFormDefault='unqualified'> elementFormDefault='unqualified'>
skipping to change at page 84, line 4 skipping to change at page 82, line 27
</xs:simpleType> </xs:simpleType>
</xs:schema> </xs:schema>
Appendix D. Differences Between Core Jabber Protocol and XMPP Appendix D. Differences Between Core Jabber Protocol and XMPP
This section is non-normative. This section is non-normative.
XMPP has been adapted from the protocols originally developed in the XMPP has been adapted from the protocols originally developed in the
Jabber open-source community, which can be thought of as "XMPP 0.9". Jabber open-source community, which can be thought of as "XMPP 0.9".
Because there exists a large installed base of Jabber implementations Because there exists a large installed base of Jabber implementations
and deployments, it may be helpful to specify the key differences and deployments, it may be helpful to specify the key differences
between Jabber and XMPP in order to expedite and encourage upgrades between Jabber and XMPP in order to expedite and encourage upgrades
of those implementations and deployments to XMPP. This section of those implementations and deployments to XMPP. This section
summarizes the core differences, while the corresponding section of summarizes the core differences, while the corresponding section of
XMPP IM [21] summarizes the differences that relate specifically to [XMPP-IM] summarizes the differences that relate specifically to
instant messaging and presence applications. instant messaging and presence applications.
D.1 Channel Encryption D.1 Channel Encryption
It is common practice in the Jabber community to use SSL for channel It is common practice in the Jabber community to use SSL for channel
encryption on ports other than 5222 and 5269 (the convention is to encryption on ports other than 5222 and 5269 (the convention is to
use ports 5223 and 5270). XMPP uses TLS over the IANA-registered use ports 5223 and 5270). XMPP uses TLS over the IANA-registered
ports for channel encryption, as defined under Stream Encryption ports for channel encryption, as defined under Use of TLS (Section 5)
(Section 5) herein. herein.
D.2 Authentication D.2 Authentication
The client-server authentication protocol developed in the Jabber The client-server authentication protocol developed in the Jabber
community uses a basic IQ interaction qualified by the community uses a basic IQ interaction qualified by the
'jabber:iq:auth' namespace (documentation of this protocol is 'jabber:iq:auth' namespace (documentation of this protocol is
contained in "JEP-0078: Non-SASL Authentication", published by the contained in "JEP-0078: Non-SASL Authentication", published by the
Jabber Software Foundation [30]). XMPP uses SASL for authentication, Jabber Software Foundation [JSF]). XMPP uses SASL for
as defined under Stream Authentication (Section 6) herein. authentication, as defined under Use of SASL (Section 6) herein.
The Jabber community does not currently possess an authentication The Jabber community does not currently possess an authentication
protocol for server-to-server communications, only the Server protocol for server-to-server communications, only the Server
Dialback (Section 8) protocol to prevent server spoofing. XMPP Dialback (Section 8) protocol to prevent server spoofing. XMPP
augments Server Dialback with a true server-to-server authentication augments Server Dialback with a true server-to-server authentication
protocol, as defined under Stream Authentication (Section 6) herein. protocol, as defined under Use of SASL (Section 6) herein.
D.3 Resource Binding D.3 Resource Binding
Resource binding in the Jabber community is handled via the Resource binding in the Jabber community is handled via the
'jabber:iq:auth' namespace that is also used for client 'jabber:iq:auth' namespace that is also used for client
authentication with a server. XMPP defines a dedicated namespace for authentication with a server. XMPP defines a dedicated namespace for
resource binding as well as the ability for a server to generate a resource binding as well as the ability for a server to generate a
resource identifier on behalf of a client, as defined under Resource resource identifier on behalf of a client, as defined under Resource
Binding (Section 7). Binding (Section 7).
D.4 JID Processing D.4 JID Processing
JID processing was somewhat loosely defined by the Jabber community JID processing was somewhat loosely defined by the Jabber community
(documentation of forbidden characters and case handling is contained (documentation of forbidden characters and case handling is contained
in "JEP-0029: Definition of Jabber Identifiers", published by the in "JEP-0029: Definition of Jabber Identifiers", published by the
Jabber Software Foundation [30]). XMPP specifies the use of Nameprep Jabber Software Foundation [JSF]). XMPP specifies the use of
[6] for domain identifiers and supplements Nameprep with two [NAMEPREP] for domain identifiers and supplements Nameprep with two
additional stringprep [7] profiles for JID processing: Nodeprep additional [STRINGPREP] profiles for JID processing: Nodeprep
(Appendix A) for node identifiers and Resourceprep (Appendix B) for (Appendix A) for node identifiers and Resourceprep (Appendix B) for
resource identifiers . resource identifiers .
D.5 Error Handling D.5 Error Handling
Stream-related errors are handled in the Jabber community via simple Stream-related errors are handled in the Jabber community via simple
CDATA text in a <stream:error/> element. In XMPP, stream-related CDATA text in a <stream:error/> element. In XMPP, stream-related
errors are handled via an extensible mechanism defined under Stream errors are handled via an extensible mechanism defined under Stream
Errors (Section 4.6) herein. Errors (Section 4.6) herein.
Stanza-related errors are handled in the Jabber community via Stanza-related errors are handled in the Jabber community via
HTTP-style error codes. In XMPP, stanza-related errors are handled HTTP-style error codes. In XMPP, stanza-related errors are handled
via an extensible mechanism defined under Stanza Errors (Section 9.3) via an extensible mechanism defined under Stanza Errors (Section 9.3)
herein. (Documentation of a mapping between Jabber and XMPP error herein. (Documentation of a mapping between Jabber and XMPP error
handling mechanisms is contained in "JEP-0086: Legacy Errors", handling mechanisms is contained in "JEP-0086: Legacy Errors",
published by the Jabber Software Foundation [30].) published by the Jabber Software Foundation [JSF].)
D.6 Internationalization D.6 Internationalization
Although use of UTF-8 has always been standard practice within the Although use of UTF-8 has always been standard practice within the
Jabber community, the community did not define mechanisms for Jabber community, the community did not define mechanisms for
specifying the language of human-readable text provided in CDATA specifying the language of human-readable text provided in CDATA
sections. XMPP specifies the use of the 'xml:lang' attribute in such sections. XMPP specifies the use of the 'xml:lang' attribute in such
contexts, as defined under Stream Attributes (Section 4.2) and contexts, as defined under Stream Attributes (Section 4.2) and
xml:lang (Section 9.1.5) herein. xml:lang (Section 9.1.5) herein.
skipping to change at page 85, line 43 skipping to change at page 84, line 18
headers. XMPP specifies inclusion of that attribute, with a value of headers. XMPP specifies inclusion of that attribute, with a value of
'1.0', as a way to signal support for the stream features '1.0', as a way to signal support for the stream features
(authentication, encryption, etc.) defined under Version Support (authentication, encryption, etc.) defined under Version Support
(Section 4.2.1) herein. (Section 4.2.1) herein.
Appendix E. Revision History Appendix E. 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.
E.1 Changes from draft-ietf-xmpp-core-18 E.1 Changes from draft-ietf-xmpp-core-19
o Fixed several typographical errors.
o Restricted values of 'type' attribute for IQ stanzas to those
defined in the schema (i.e., changed SHOULD to MUST) to ensure
consistency with text in XMPP IM.
o Added reference to RFC 3548.
o Replaced RFC 2222 reference with reference to
draft-ietf-sasl-rfc2222bis.
o Further clarified role and usage of user names in SASL mechanisms.
o Added mention of 'code' attribute on error element.
o Clarified several sentences in the dialback narrative.
o Clarified use of stringprep profiles and added reference to RFC
3490.
o Added security consideration regarding lack of SASL channel
binding to TLS per discussion at IETF 58 meeting.
o Adjusted formatting to conform to RFC Editor requirements.
E.2 Changes from draft-ietf-xmpp-core-18
o Added the 'xml:lang' attribute to the root <stream/> element per o Added the 'xml:lang' attribute to the root <stream/> element per
previous consensus and list discussion. previous consensus and list discussion.
o Changed "jabber-server" and "jabber-client" service names to
"xmpp-server" and "xmpp-client".
o Added the <gone/>, <not-acceptable/>, and <redirect/> stanza o Added the <gone/>, <not-acceptable/>, and <redirect/> stanza
errors. errors.
o Changed dataype of <see-other-host/> stream error and of <gone/> o Changed dataype of <see-other-host/> stream error and of <gone/>
and <redirect/> stanza errors to xs:string so that these elements and <redirect/> stanza errors to xs:string so that these elements
may contain programmatic information. may contain programmatic information.
o Removed <invalid-realm/> and <bad-protocol/> SASL errors. o Removed <invalid-realm/> and <bad-protocol/> SASL errors.
o Removed references to RFC 952 and RFC 1123 (domain name format is o Removed references to RFC 952 and RFC 1123 (domain name format is
skipping to change at page 86, line 33 skipping to change at page 85, line 38
o Removed recommendation that TLS and SASL security layer should not o Removed recommendation that TLS and SASL security layer should not
both be used simultaneously. both be used simultaneously.
o Added subsection to Security Considerations regarding use of o Added subsection to Security Considerations regarding use of
base64 in SASL. base64 in SASL.
o Specified rules regarding inclusion of username in SASL o Specified rules regarding inclusion of username in SASL
negotiation. negotiation.
o Adjusted content related to SASL authorization identities, since o Adjusted content related to SASL authorization identities, since
the previous text did not track RFC2222bis. the previous text did not track SASL.
o Added section on resource binding to compensate for changes to o Added section on resource binding to compensate for changes to
SASL authorization identity text. SASL authorization identity text.
o Specified ABNF for JIDs. o Specified ABNF for JIDs.
o Checked all references. o Checked all references.
o Completed a thorough proofreading and consistency check of the o Completed a thorough proofreading and consistency check of the
entire text. entire text.
E.2 Changes from draft-ietf-xmpp-core-17 E.3 Changes from draft-ietf-xmpp-core-17
o Specified that UTF-8 is the only allowable encoding. o Specified that UTF-8 is the only allowable encoding.
o Added stream errors for <bad-namespace-prefix/>, <invalid-xml/>, o Added stream errors for <bad-namespace-prefix/>, <invalid-xml/>,
and <restricted-xml/>, as well as a <bad-format/> error for and <restricted-xml/>, as well as a <bad-format/> error for
generic XML error conditions. generic XML error conditions.
o Folded Nodeprep and Resourceprep profiles into this document. o Folded Nodeprep and Resourceprep profiles into this document.
o Moved most delivery handling rules from XMPP IM to XMPP Core. o Moved most delivery handling rules from XMPP IM to XMPP Core.
o Moved detailed stanza syntax descriptions from XMPP Core to XMPP o Moved detailed stanza syntax descriptions from XMPP Core to XMPP
IM. IM.
o Moved stanza schemas from XMPP Core to XMPP IM. o Moved stanza schemas from XMPP Core to XMPP IM.
E.3 Changes from draft-ietf-xmpp-core-16 E.4 Changes from draft-ietf-xmpp-core-16
o Added <conflict/> and <unsupported-encoding/> stream errors. o Added <conflict/> and <unsupported-encoding/> stream errors.
o Changed the datatype for the <see-other-host/> and o Changed the datatype for the <see-other-host/> and
<unsupported-version/> stream errors from 'xs:string' to 'empty'. <unsupported-version/> stream errors from 'xs:string' to 'empty'.
o Further clarified server handling of the basic stanza kinds. o Further clarified server handling of the basic stanza kinds.
o Further clarified character encoding rules per list discussion. o Further clarified character encoding rules per list discussion.
skipping to change at page 87, line 37 skipping to change at page 86, line 44
o Added stream closure to SASL failure cases in order to mirror o Added stream closure to SASL failure cases in order to mirror
handling of TLS failures. handling of TLS failures.
o Added section on compliance requirements for server and client o Added section on compliance requirements for server and client
implementations. implementations.
o Added non-normative section on differences between Jabber usage o Added non-normative section on differences between Jabber usage
and XMPP specifications. and XMPP specifications.
E.4 Changes from draft-ietf-xmpp-core-15 E.5 Changes from draft-ietf-xmpp-core-15
o Added <connection-timeout/> and <policy-violation/> stream errors. o Added <connection-timeout/> and <policy-violation/> stream errors.
o Added <aborted/> SASL error and clarified <bad-protocol/> error. o Added <aborted/> SASL error and clarified <bad-protocol/> error.
o Made 'id' required for IQ stanzas. o Made 'id' required for IQ stanzas.
E.5 Changes from draft-ietf-xmpp-core-14 E.6 Changes from draft-ietf-xmpp-core-14
o Added SRV lookup for client-to-server communications. o Added SRV lookup for client-to-server communications.
o Changed server SRV record to conform to RFC 2782; specifically, o Changed server SRV record to conform to RFC 2782; specifically,
the service identifier was changed from 'jabber' to the service identifier was changed from 'jabber' to
'jabber-server'. 'jabber-server'.
E.6 Changes from draft-ietf-xmpp-core-13 E.7 Changes from draft-ietf-xmpp-core-13
o Clarified stream restart after successful TLS and SASL o Clarified stream restart after successful TLS and SASL
negotiation. negotiation.
o Clarified requirement for resolution of DNS hostnames. o Clarified requirement for resolution of DNS hostnames.
o Clarified text regarding namespaces. o Clarified text regarding namespaces.
o Clarified examples regarding empty <stream:features/> element. o Clarified examples regarding empty <stream:features/> element.
o Added several more SASL error conditions. o Added several more SASL error conditions.
o Changed <invalid-xml/> stream error to <improper-addressing/> and o Changed <invalid-xml/> stream error to <improper-addressing/> and
added to schema. added to schema.
o Made small editorial changes and fixed several schema errors. o Made small editorial changes and fixed several schema errors.
E.7 Changes from draft-ietf-xmpp-core-12 E.8 Changes from draft-ietf-xmpp-core-12
o Moved server dialback to a separate section; clarified its o Moved server dialback to a separate section; clarified its
security characteristics and its role in the protocol. security characteristics and its role in the protocol.
o Adjusted error handling syntax and semantics per list discussion. o Adjusted error handling syntax and semantics per list discussion.
o Further clarified length of node identifiers and total length of o Further clarified length of node identifiers and total length of
JIDs. JIDs.
o Documented message type='normal'. o Documented message type='normal'.
o Corrected several small errors in the TLS and SASL sections. o Corrected several small errors in the TLS and SASL sections.
o Corrected several errors in the schemas. o Corrected several errors in the schemas.
E.8 Changes from draft-ietf-xmpp-core-11 E.9 Changes from draft-ietf-xmpp-core-11
o Corrected several small errors in the TLS and SASL sections. o Corrected several small errors in the TLS and SASL sections.
o Made small editorial changes and fixed several schema errors. o Made small editorial changes and fixed several schema errors.
E.9 Changes from draft-ietf-xmpp-core-10 E.10 Changes from draft-ietf-xmpp-core-10
o Adjusted TLS content regarding certificate validation process. o Adjusted TLS content regarding certificate validation process.
o Specified that stanza error extensions for specific applications o Specified that stanza error extensions for specific applications
are to be properly namespaced children of the relevant descriptive are to be properly namespaced children of the relevant descriptive
element. element.
o Clarified rules for inclusion of the 'id' attribute. o Clarified rules for inclusion of the 'id' attribute.
o Specified that the 'xml:lang' attribute SHOULD be included (per o Specified that the 'xml:lang' attribute SHOULD be included (per
list discussion). list discussion).
o Made small editorial changes and fixed several schema errors. o Made small editorial changes and fixed several schema errors.
E.10 Changes from draft-ietf-xmpp-core-09 E.11 Changes from draft-ietf-xmpp-core-09
o Fixed several dialback error conditions. o Fixed several dialback error conditions.
o Cleaned up rules regarding TLS and certificate processing based on o Cleaned up rules regarding TLS and certificate processing based on
off-list feedback. off-list feedback.
o Changed <stream-condition/> and <stanza-condition/> elements to o Changed <stream-condition/> and <stanza-condition/> elements to
<condition/>. <condition/>.
o Added or modified several stream and stanza error conditions. o Added or modified several stream and stanza error conditions.
o Specified only one child allowed for IQ, or two if type="error". o Specified only one child allowed for IQ, or two if type="error".
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
E.11 Changes from draft-ietf-xmpp-core-08 E.12 Changes from draft-ietf-xmpp-core-08
o Incorporated list discussion regarding addressing, SASL, TLS, TCP, o Incorporated list discussion regarding addressing, SASL, TLS, TCP,
dialback, namespaces, extensibility, and the meaning of 'ignore' dialback, namespaces, extensibility, and the meaning of 'ignore'
for routers and recipients. for routers and recipients.
o Specified dialback error conditions. o Specified dialback error conditions.
o Made small editorial changes to address RFC Editor requirements. o Made small editorial changes to address RFC Editor requirements.
E.12 Changes from draft-ietf-xmpp-core-07 E.13 Changes from draft-ietf-xmpp-core-07
o Made several small editorial changes. o Made several small editorial changes.
E.13 Changes from draft-ietf-xmpp-core-06 E.14 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 [24]. to the format defined in The IETF XML Registry.
o Removed note to RFC Editor regarding provisional namespace names. o Removed note to RFC Editor regarding provisional namespace names.
E.14 Changes from draft-ietf-xmpp-core-05 E.15 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.
E.15 Changes from draft-ietf-xmpp-core-04 E.16 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.
E.16 Changes from draft-ietf-xmpp-core-03 E.17 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.
E.17 Changes from draft-ietf-xmpp-core-02 E.18 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".
E.18 Changes from draft-ietf-xmpp-core-01 E.19 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' o Corrected error in Use of SASL regarding 'version' attribute.
attribute.
o Made numerous small editorial changes. o Made numerous small editorial changes.
E.19 Changes from draft-ietf-xmpp-core-00 E.20 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.
E.20 Changes from draft-miller-xmpp-core-02 E.21 Changes from draft-miller-xmpp-core-02
o Brought Stream Authentication section into line with discussion on o Brought Use of SASL section into line with discussion on list and
list and at IETF 55 meeting. 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.
o Specified that the response to an IQ stanza of type "get" or "set" o Specified that the response to an IQ stanza of type "get" or "set"
must be an IQ stanza of type "result" or "error". must be an IQ stanza of type "result" or "error".
 End of changes. 329 change blocks. 
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