draft-ietf-xmpp-core-11.txt   draft-ietf-xmpp-core-12.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft J. Miller Internet-Draft J. Miller
Expires: October 26, 2003 Jabber Software Foundation Expires: November 2, 2003 Jabber Software Foundation
April 27, 2003 May 04, 2003
XMPP Core XMPP Core
draft-ietf-xmpp-core-11 draft-ietf-xmpp-core-12
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
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on October 26, 2003. This Internet-Draft will expire on November 2, 2003.
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 document describes the core features of the Extensible Messaging This document describes the core features of the Extensible Messaging
and Presence Protocol (XMPP), a protocol for streaming XML elements and Presence Protocol (XMPP), a protocol for streaming XML elements
in order to exchange messages and presence information in close to in order to exchange messages and presence information in close to
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2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . 8 3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . 8
3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . . 8 3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . . 8
3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . . 8
3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . . 9 3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . . 9
4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . 10 4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2 Stream Attributes . . . . . . . . . . . . . . . . . . . . . 11 4.2 Stream Attributes . . . . . . . . . . . . . . . . . . . . . 11
4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . . 12 4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . . 12
4.3.1 Stream Namespace Declaration . . . . . . . . . . . . . . . . 12
4.3.2 Default Namespace Declaration . . . . . . . . . . . . . . . 13
4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . . 13 4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . . 13
4.5 Stream Errors . . . . . . . . . . . . . . . . . . . . . . . 14 4.5 Stream Errors . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.5.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.5.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 16 4.5.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 16
4.6 Simple Streams Example . . . . . . . . . . . . . . . . . . . 16 4.6 Simple Streams Example . . . . . . . . . . . . . . . . . . . 16
5. Stream Encryption . . . . . . . . . . . . . . . . . . . . . 19 5. Stream Encryption . . . . . . . . . . . . . . . . . . . . . 19
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 20
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6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 27 6.1.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 29 6.1.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 29
6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . . 30 6.1.4 Client-to-Server Example . . . . . . . . . . . . . . . . . . 30
6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . . 32 6.1.5 Server-to-Server Example . . . . . . . . . . . . . . . . . . 32
6.2 Dialback Authentication . . . . . . . . . . . . . . . . . . 35 6.2 Dialback Authentication . . . . . . . . . . . . . . . . . . 35
6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . . 37 6.2.1 Dialback Protocol . . . . . . . . . . . . . . . . . . . . . 37
7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 42 7. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 42
7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . . 42 7.2 Common Attributes . . . . . . . . . . . . . . . . . . . . . 42
7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.2.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . . 44 7.3 Message Stanzas . . . . . . . . . . . . . . . . . . . . . . 44
7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . . 44 7.3.1 Types of Message . . . . . . . . . . . . . . . . . . . . . . 44
7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 44 7.3.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . . 46 7.4 Presence Stanzas . . . . . . . . . . . . . . . . . . . . . . 46
7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . . 46 7.4.1 Types of Presence . . . . . . . . . . . . . . . . . . . . . 46
7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 47 7.4.2 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.5 IQ Stanzas . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . . 49 7.5.2 Types of IQ . . . . . . . . . . . . . . . . . . . . . . . . 48
7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.5.3 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . . 50 7.6 Extended Namespaces . . . . . . . . . . . . . . . . . . . . 49
7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 51 7.7 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 50
7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 7.7.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 7.7.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 52 7.7.3 Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 53 7.7.4 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 52
8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 54 8. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 54
8.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 54 8.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 54
8.2 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . 54 8.2 Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 54 8.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.4 Character Encodings . . . . . . . . . . . . . . . . . . . . 55 8.4 Character Encodings . . . . . . . . . . . . . . . . . . . . 55
8.5 Inclusion of Text Declaration . . . . . . . . . . . . . . . 55 8.5 Inclusion of Text Declaration . . . . . . . . . . . . . . . 55
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 56 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 56
9.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . . 56 9.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . . 56
9.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . . 56 9.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . . 56
9.3 XML Namespace Name for Stream Errors . . . . . . . . . . . . 56 9.3 XML Namespace Name for Stream Errors . . . . . . . . . . . . 56
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Normative References . . . . . . . . . . . . . . . . . . . . 61 Normative References . . . . . . . . . . . . . . . . . . . . 61
Informative References . . . . . . . . . . . . . . . . . . . 63 Informative References . . . . . . . . . . . . . . . . . . . 63
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 63 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 63
A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 65 A. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 65
A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . . 65 A.1 Streams namespace . . . . . . . . . . . . . . . . . . . . . 65
A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 66 A.2 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 66
A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 66 A.3 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 66
A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 67 A.4 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 67
A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . . 68 A.5 Client namespace . . . . . . . . . . . . . . . . . . . . . . 68
A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . . 72 A.6 Server namespace . . . . . . . . . . . . . . . . . . . . . . 72
A.7 Stream error namespace . . . . . . . . . . . . . . . . . . . 75 A.7 Stream error namespace . . . . . . . . . . . . . . . . . . . 76
A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . . 76 A.8 Stanza error namespace . . . . . . . . . . . . . . . . . . . 77
B. Revision History . . . . . . . . . . . . . . . . . . . . . . 78 B. Revision History . . . . . . . . . . . . . . . . . . . . . . 79
B.1 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . . 78 B.1 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . . 79
B.2 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . . 78 B.2 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . . 79
B.3 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . . 78 B.3 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . . 79
B.4 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . . 78 B.4 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . . 80
B.5 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . . 79 B.5 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . . 80
B.6 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 79 B.6 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . . 80
B.7 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 79 B.7 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 80
B.8 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 79 B.8 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 80
B.9 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 80 B.9 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 81
B.10 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 80 B.10 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 81
B.11 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 80 B.11 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 81
Intellectual Property and Copyright Statements . . . . . . . 82 B.12 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 81
Intellectual Property and Copyright Statements . . . . . . . 83
1. Introduction 1. Introduction
1.1 Overview 1.1 Overview
The Extensible Messaging and Presence Protocol (XMPP) is an open XML The Extensible Messaging and Presence Protocol (XMPP) is an open XML
[1] protocol for near-real-time messaging, presence, and [1] protocol for near-real-time messaging, presence, and
request-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
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identifying namespaces and other protocol syntax. Jabber[tm] is a identifying namespaces and other protocol syntax. Jabber[tm] is a
registered trademark of Jabber, Inc. Jabber, Inc. grants permission registered trademark of Jabber, Inc. Jabber, Inc. grants permission
to the IETF for use of the Jabber trademark in association with this to the IETF for use of the Jabber trademark in association with this
specification and its successors, if any. specification and its successors, if any.
2. Generalized Architecture 2. Generalized Architecture
2.1 Overview 2.1 Overview
Although XMPP is not wedded to any specific network architecture, to Although XMPP is not wedded to any specific network architecture, to
this point it has usually been implemented via a typical this point it usually has been implemented via a typical
client-server architecture, wherein a client utilizing XMPP accesses client-server architecture, wherein a client utilizing XMPP accesses
a server over a TCP [4] socket. a server over a TCP [4] socket.
The following diagram provides a high-level overview of this The following diagram provides a high-level overview of this
architecture (where "-" represents communications that use XMPP and architecture (where "-" represents communications that use XMPP and
"=" represents communications that use any other protocol). "=" represents communications that use any other protocol).
C1 - S1 - S2 - C3 C1 - S1 - S2 - C3
/ \ / \
C2 - G1 = FN1 = FC1 C2 - G1 = FN1 = FC1
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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 polling or some other mechanism), this specification defines a HTTP polling or some other mechanism), this specification defines a
binding for XMPP to TCP only. Multiple resources (e.g., devices or binding for XMPP to TCP only. Multiple resources (e.g., devices or
locations) MAY connect simultaneously to a server on behalf of each locations) MAY connect simultaneously to a server on behalf of each
authorized client, with each resource connecting over a discrete TCP authorized client, with each resource connecting over a discrete TCP
socket and differentiated by the resource identifier of a JID socket and differentiated by the resource identifier of a Jabber
(Section 3) (e.g., user@domain/home vs. user@domain/work). The port Identifier (e.g., user@domain/home vs. user@domain/work) as defined
registered with the IANA [5] for connections between a Jabber client under Section 3. The port registered with the IANA [5] for
and a Jabber server is 5222. connections between a Jabber client and a Jabber server is 5222.
2.4 Gateway 2.4 Gateway
A gateway is a special-purpose server-side service whose primary A gateway is a special-purpose server-side service whose primary
function is to translate XMPP into the protocol used by a foreign function is to translate XMPP into the protocol used by a foreign
(non-XMPP) messaging system, as well as to translate the return data (non-XMPP) messaging system, as well as to translate the return data
back into XMPP. Examples are gateways to Internet Relay Chat (IRC), back into XMPP. Examples are gateways to Internet Relay Chat (IRC),
Short Message Service (SMS), SMTP, and legacy instant messaging Short Message Service (SMS), SMTP, and legacy instant messaging
networks such as AIM, ICQ, MSN Messenger, and Yahoo! Instant networks such as AIM, ICQ, MSN Messenger, and Yahoo! Instant
Messenger. Communications between gateways and servers, and between Messenger. Communications between gateways and servers, and between
gateways and the foreign messaging system, are not defined in this gateways and the foreign messaging system, are not defined in this
document. document.
2.5 Network 2.5 Network
Because each server is identified by a network address (typically a Because each server is identified by a network address and because
DNS hostname) and because server-to-server communications are a server-to-server communications are a straightforward extension of
straightforward extension of the client-to-server protocol, in the client-to-server protocol, in practice the system consists of a
practice the system consists of a network of servers that network of servers that inter-communicate. Thus user-a@domain1 is
inter-communicate. Thus user-a@domain1 is able to exchange messages, able to exchange messages, presence, and other information with
presence, and other information with user-b@domain2. This pattern is user-b@domain2. This pattern is familiar from messaging protocols
familiar from messaging protocols (such as SMTP) that make use of (such as SMTP) that make use of network addressing standards. There
network addressing standards. There are two methods for negotiating a are two methods for negotiating a connection between any two servers:
connection between any two servers: primarily SASL authentication primarily SASL authentication (Section 6.1) and secondarily server
(Section 6.1) and secondarily server dialback (Section 6.2). dialback (Section 6.2).
3. Addressing Scheme 3. Addressing Scheme
3.1 Overview 3.1 Overview
An entity is anything that can be considered a network endpoint An entity is anything that can be considered a network endpoint
(i.e., an ID on the network) and that can communicate using XMPP. All (i.e., an ID on the network) and that can communicate using XMPP. All
such entities are uniquely addressable in a form that is consistent such entities are uniquely addressable in a form that is consistent
with RFC 2396 [24]. In particular, a valid Jabber Identifier (JID) with RFC 2396 [24]. In particular, a valid Jabber Identifier (JID)
contains a set of ordered elements formed of a domain identifier, contains a set of ordered elements formed of a domain identifier,
node identifier, and resource identifier in the following format: node identifier, and resource identifier in the following format:
[node@]domain[/resource]. [node@]domain[/resource].
All JIDs are based on the foregoing structure. The most common use of All JIDs are based on the foregoing structure. The most common use of
this structure is to identify an IM user, the server to which the this structure is to identify an IM user, the server to which the
user connects, and the user's active session or connection (e.g., a user connects, and the user's active session or connection (e.g., a
specific client) in the form of user@domain/resource. However, node specific client) in the form of <user@domain/resource>. However, node
types other than clients are possible; for example, a specific chat types other than clients are possible; for example, a specific chat
room offered by a multi-user chat service could be addressed as room offered by a multi-user chat service could be addressed as
<room@service> (where "room" is the name of the chat room and <room@service> (where "room" is the name of the chat room and
"service" is the hostname of the multi-user chat service) and a "service" is the hostname of the multi-user chat service) and a
specific occupant of such a room could be addressed as <room@service/ specific occupant of such a room could be addressed as <room@service/
nick> (where "nick" is the occupant's room nickname). Many other JID nick> (where "nick" is the occupant's room nickname). Many other JID
types are possible (e.g., <domain/resource> could be a server-side types are possible (e.g., <domain/resource> could be a server-side
script or service). script or service).
3.2 Domain Identifier 3.2 Domain Identifier
skipping to change at page 9, line 16 skipping to change at page 9, line 16
a node identifier is addressed within the context of a specific a node identifier is addressed within the context of a specific
domain; within IM applications of XMPP this address is called a "bare domain; within IM applications of XMPP this address is called a "bare
JID" and is of the form <user@domain>. JID" and is of the form <user@domain>.
A node identifier MUST be no more than 1023 bytes in length and MUST A node identifier MUST be no more than 1023 bytes in length and MUST
conform to the nodeprep [10] profile of stringprep [9]. conform to the nodeprep [10] profile of stringprep [9].
3.4 Resource Identifier 3.4 Resource Identifier
The resource identifier is an optional tertiary identifier, which may The resource identifier is an optional tertiary identifier, which may
modify either a "user@domain" or mere "domain" address. It usually modify either a <user@domain> or mere <domain> address. It usually
represents a specific session, connection (e.g., a device or represents a specific session, connection (e.g., a device or
location), or object (e.g., a participant in a multi-user chat room) location), or object (e.g., a participant in a multi-user chat room)
belonging to the entity associated with a node identifier. A resource belonging to the entity associated with a node identifier. A resource
identifier is typically defined by a client implementation and is identifier is opaque to both servers and other clients, and is
opaque to both servers and other clients. An entity may maintain typically defined by a client implementation as the authzid value
provided during stream authentication. An entity may maintain
multiple resources simultaneously. multiple resources simultaneously.
A resource identifier MUST be no more than 1023 bytes in length and A resource identifier MUST be no more than 1023 bytes in length and
MUST conform to the resourceprep [11] profile of stringprep [9]. MUST conform to the resourceprep [11] profile of stringprep [9].
4. XML Streams 4. XML Streams
4.1 Overview 4.1 Overview
Two fundamental concepts make possible the rapid, asynchronous Two fundamental concepts make possible the rapid, asynchronous
exchange of relatively small payloads of structured information exchange of relatively small payloads of structured information
between presence-aware entities: XML streams and XML stanzas. The between presence-aware entities: XML streams and XML stanzas. These
terms may be defined as follows: terms may be defined as follows:
Definition of XML stream: An XML stream is a container for the Definition of XML Stream: An XML stream is a container for the
exchange of XML elements between any two entities over a network. exchange of XML elements between any two entities over a network.
An XML stream is negotiated from an initiating entity (usually a An XML stream is negotiated from an initiating entity (usually a
client or server) to a receiving entity (usually a server), client or server) to a receiving entity (usually a server),
normally over a TCP socket, and corresponds to the initiating normally over a TCP socket, and corresponds to the initiating
entity's "session" with the receiving entity. The start of the XML entity's "session" with the receiving entity. The start of the XML
stream is denoted unambiguously by an opening XML <stream> tag stream is denoted unambiguously by an opening XML <stream> tag
with appropriate attributes and namespace declarations, and the with appropriate attributes and namespace declarations, and the
end of the XML stream is denoted unambiguously be a closing XML </ end of the XML stream is denoted unambiguously by a closing XML </
stream> tag. An XML stream is unidirectional; in order to enable stream> tag. An XML stream is unidirectional; in order to enable
bidirectional information exchange, the initiating entity and bidirectional information exchange, the initiating entity and
receiving entity must negotiate one stream in each direction, receiving entity must negotiate one stream in each direction,
normally over the same TCP connection. normally over the same TCP connection.
Definition of XML stanza: An XML stanza is a discrete semantic unit Definition of XML Stanza: An XML stanza is a discrete semantic unit
of structured information that is sent from one entity to another of structured information that is sent from one entity to another
over an XML stream. An XML stanza exists at the direct child level over an XML stream. An XML stanza exists at the direct child level
of the root <stream/> element and is said to be well-balanced if of the root <stream/> element and is said to be well-balanced if
it matches production [43] content of the XML specification [1]). it matches production [43] content of the XML specification [1]).
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 (e.g., <presence>), and the end of element start tag at depth=1 of the XML stream (e.g., <presence>),
any XML stanza is denoted unambiguously by the corresponding close and the end of any XML stanza is denoted unambiguously by the
tag at depth=1 (e.g., </presence>). An XML stanza MAY contain corresponding close tag at depth=1 (e.g., </presence>). An XML
child elements (with accompanying attributes, elements, and CDATA) stanza MAY contain child elements (with accompanying attributes,
as necessary in order to convey the desired information. elements, and CDATA) as necessary in order to convey the desired
information.
Consider the example of a client's session with a server. In order to Consider the example of a client's session with a server. In order to
connect to a server, a client must initiate an XML stream by sending connect to a server, a client must initiate an XML stream by sending
an opening <stream> tag to the server, optionally preceded by a text an opening <stream> tag to the server, optionally preceded by a text
declaration specifying the XML version supported and the character declaration specifying the XML version supported and the character
encoding. The server SHOULD then reply with a second XML stream back encoding (see also Section 8.4). The server SHOULD then reply with a
to the client, again optionally preceded by a text declaration. Once second XML stream back to the client, again optionally preceded by a
the client has authenticated with the server (see Section 6), the text declaration. Once the client has authenticated with the server
client MAY send an unlimited number of XML stanzas over the stream to (see Section 6), the client MAY send an unlimited number of XML
any recipient on the network. When the client desires to close the stanzas over the stream to any recipient on the network. When the
stream, it simply sends a closing </stream> tag to the server client desires to close the stream, it simply sends a closing </
(alternatively, the session may be closed by the server), after which stream> tag to the server (alternatively, the stream may be closed by
both the client and server SHOULD close the underlying TCP connection the server), after which both the client and server SHOULD close the
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
the server and one from the server to the client. From this the server and one from the server to the client. From this
perspective, the root <stream/> element can be considered the perspective, the root <stream/> element can be considered the
document entity for each "document", and the two "documents" are document entity for each "document", and the two "documents" are
built up through the accumulation of XML stanzas sent over the two built up through the accumulation of XML stanzas sent over the two
XML streams. However, this perspective is a convenience only, and XML streams. However, this perspective is a convenience only, and
XMPP does not deal in documents but in XML streams and XML stanzas. XMPP does not deal in documents but in XML streams and XML stanzas.
In essence, then, an XML stream acts as an envelope for all the XML In essence, then, an XML stream acts as an envelope for all the XML
stanzas sent during a session. We can represent this graphically as stanzas sent during a session. We can represent this graphically as
follows: follows:
|-------------------| |--------------------|
| <stream> | | <stream> |
|-------------------| |--------------------|
| <message to=''> | | <presence> |
| <body/> |
| </message> |
|-------------------|
| <presence to=''> |
| <show/> | | <show/> |
| </presence> | | </presence> |
|-------------------| |--------------------|
| <iq to=''> | | <message to='foo'> |
| <body/> |
| </message> |
|--------------------|
| <iq to='bar'> |
| <query/> | | <query/> |
| </iq> | | </iq> |
|-------------------| |--------------------|
| ... | | ... |
|-------------------| |--------------------|
| </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 XMPP address of the receiving entity. There MUST be set to the XMPP address of the receiving entity. There
SHOULD be no 'to' attribute set in the XML stream header by which SHOULD be no 'to' attribute set in the XML stream header by which
the receiving entity replies to the initiating entity; however, if the receiving entity replies to the initiating entity; however, if
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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 XMPP address of the receiving entity granting MUST be set to the XMPP address of the receiving entity granting
access to the initiating entity. There SHOULD be no 'from' access to the initiating entity. There SHOULD be no 'from'
attribute on the XML stream header sent from the initiating entity attribute on the XML stream header sent from the initiating entity
to the receiving entity; however, if a 'from' attribute is to the receiving entity; however, if a 'from' attribute is
included, it SHOULD be 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 session to function as a session key for the initiating entity's streams
with the receiving entity. There SHOULD be no 'id' attribute on with the receiving entity. There SHOULD be no 'id' attribute on
the XML stream header sent from the initiating entity to the the XML stream header sent from the initiating entity to the
receiving entity; however, if an 'id' attribute is included, it receiving entity; however, if an 'id' attribute is included, it
SHOULD be silently ignored by the receiving entity. SHOULD be silently ignored by the receiving entity.
o version -- The 'version' attribute MAY be used in the XML stream o version -- If the initiating entity complies with the protocol
header from the initiating entity to the receiving entity in order defined herein, it MUST include a 'version' attribute in the XML
signal compliance with the protocol defined herein; this is done stream header it sends to the receiving entity, and it MUST set
by setting the value of the attribute to "1.0". If the initiating the value of the 'version' attribute to "1.0". If the initiating
entity includes the version attribute and the receiving entity entity includes the version attribute and the receiving entity
supports XMPP 1.0, the receiving entity MUST reciprocate by supports XMPP 1.0, the receiving entity MUST reciprocate by
including the attribute in its response. including the attribute in its response.
We can summarize these values as follows: We can summarize these values as follows:
| initiating to receiving | receiving to initiating | initiating to receiving | receiving to initiating
------------------------------------------------------------ ------------------------------------------------------------
to | hostname of receiver | silently ignored to | hostname of receiver | silently ignored
from | silently ignored | hostname of receiver from | silently ignored | hostname of receiver
id | silently ignored | session key id | silently ignored | session key
version | signals XMPP 1.0 support | signals XMPP 1.0 support version | signals XMPP 1.0 support | signals XMPP 1.0 support
4.3 Namespace Declarations 4.3 Namespace Declarations
The stream element MAY contain namespace declarations as defined in The stream element MUST possess both a stream namespace declaration
the XML namespaces specification [12]. and a default namespace declaration (as "namespace declaration" is
defined in the XML namespaces specification [12]).
4.3.1 Stream Namespace Declaration
A stream namespace declaration (e.g., 'xmlns:stream') is REQUIRED in A stream namespace declaration (e.g., 'xmlns:stream') is REQUIRED in
both XML streams. A compliant entity SHOULD accept any namespace both XML streams. A compliant entity SHOULD accept any namespace
prefix on the <stream/> element; however, for historical reasons some prefix on the <stream/> element; however, for historical reasons some
entities MAY accept only a 'stream' prefix, resulting in the use of a entities MAY accept only a 'stream' prefix, resulting in the use of a
<stream:stream/> element as the stream root. The name of the stream <stream:stream/> element as the stream root. The name of the stream
namespace MUST be "http://etherx.jabber.org/streams". namespace MUST be "http://etherx.jabber.org/streams".
4.3.2 Default Namespace Declaration
A default namespace declaration ('xmlns') is REQUIRED and is used in A default namespace declaration ('xmlns') is REQUIRED and is used in
both XML streams in order to define the allowable first-level both XML streams in order to define the allowable first-level
children of the root stream element for both streams. This namespace children of the root stream element for both streams. This namespace
declaration MUST be the same for the initiating stream and the declaration MUST be the same for the initiating stream and the
responding stream so that both streams are scoped consistently. The responding stream so that both streams are scoped consistently. The
default namespace declaration applies to the stream and all stanzas default namespace declaration applies to the stream and all stanzas
sent within a stream (unless explicitly scoped by another namespace). sent within a stream (unless explicitly scoped by another namespace).
Since XML streams function as containers for any XML stanzas sent Since XML streams function as containers for any XML stanzas sent
asynchronously between network endpoints, it should be possible to asynchronously between network endpoints, it should be possible to
scope an XML stream with any default namespace declaration (i.e., it scope an XML stream with any default namespace declaration. At a
should be possible to send any properly-namespaced XML stanza over an minimum, a compliant implementation MUST support the following two
XML stream). At a minimum, a compliant implementation MUST support namespaces (for historical reasons, some implementations MAY support
the following two namespaces (for historical reasons, some only these two default namespaces):
implementations MAY support only these two default namespaces):
o jabber:client -- this default namespace is declared when the o jabber:client -- this default namespace is declared when the
stream is used for communications between a client and a server stream is used for communications between a client and a server
o jabber:server -- this default namespace is declared when the o jabber:server -- this default namespace is declared when the
stream is used for communications between two servers stream is used for communications between two servers
The jabber:client and jabber:server namespaces are nearly identical The 'jabber:client' and 'jabber:server' namespaces are nearly
but are used in different contexts (client-to-server communications identical but are used in different contexts (client-to-server
for jabber:client and server-to-server communications for communications for 'jabber:client' and server-to-server
jabber:server). The only difference between the two is that the 'to' communications for 'jabber:server'). The only difference between the
and 'from' attributes are OPTIONAL on stanzas sent within two is that the 'to' and 'from' attributes are OPTIONAL on stanzas
jabber:client, whereas they are REQUIRED on stanzas sent within sent within 'jabber:client', whereas they are REQUIRED on stanzas
jabber:server. If a compliant implementation accepts a stream that is sent within 'jabber:server'. If a compliant implementation accepts a
scoped by the 'jabber:client' or 'jabber:server' namespace, it MUST stream that is scoped by the 'jabber:client' or 'jabber:server'
support all three core stanza types (message, presence, and IQ) as namespace, it MUST support all three core stanza types (message,
described herein and defined in the schema. presence, and IQ) as described herein and defined in the schema.
4.4 Stream Features 4.4 Stream Features
The root stream element MAY contain a features child element (e.g., If the initiating entity sends a "version='1.0'" flag in its
<stream:features/> if the stream namespace prefix is 'stream'). This
is used to communicate generic stream-level capabilities including
stream-level features that can be negotiated as the streams are set
up. If the initiating entity sends a "version='1.0'" flag in its
initiating stream element, the receiving entity MUST send a features initiating stream element, the receiving entity MUST send a features
child element to the initiating entity if there are any capabilities child element to the initiating entity in order to announce any
that need to be advertised or features that can be negotiated for the stream-level features that can be negotiated (or capabilities that
stream. Currently this is used for SASL and TLS negotiation only, but otherwise need to be advertised). Currently this is used for SASL and
it could be used for other negotiable features in the future (usage TLS negotiation only, but it could be used for other negotiable
is defined under Stream Encryption (Section 5) and Stream features in the future (usage is defined under Stream Encryption
Authentication (Section 6) below). If an entity does not understand (Section 5) and Stream Authentication (Section 6) below). If an
or support some features, it SHOULD silently ignore them. entity does not understand or support some features, it SHOULD
silently ignore them.
4.5 Stream Errors 4.5 Stream Errors
The root stream element MAY contain an error child element (e.g., The root stream element MAY contain an error child element (e.g.,
<stream:error/> if the stream namespace prefix is 'stream'). The <stream:error/> if the stream namespace prefix is 'stream'). The
error child MUST be sent by a compliant entity (usually a server error child MUST be sent by a compliant entity (usually a server
rather than a client) if it perceives that a stream-level error has rather than a client) if it perceives that a stream-level error has
occurred. occurred.
4.5.1 Rules 4.5.1 Rules
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initiating entity in the stream header corresponds to a hostname initiating entity in the stream header corresponds to a hostname
that is no longer hosted by the server; the associated class is that is no longer hosted by the server; the associated class is
"address". "address".
o <host-unknown/> -- the value of the 'to' attribute provided by the o <host-unknown/> -- the value of the 'to' attribute provided by the
initiating entity in the stream header does not correspond to a initiating entity in the stream header does not correspond to a
hostname that is hosted by the server; the associated class is hostname that is hosted by the server; the associated class is
"address". "address".
o <internal-server-error/> -- the server has experienced a o <internal-server-error/> -- the server has experienced a
misconfiguration or an otherwise-undefined internal server error misconfiguration or an otherwise-undefined internal error that
that prevents it from servicing the stream; the associated class prevents it from servicing the stream; the associated class is
is "server". "server".
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; the associated class is not match an ID previously provided; the associated class is
"format". "format".
o <invalid-namespace/> -- the stream namespace name is something o <invalid-namespace/> -- the stream namespace name is something
other than "http://etherx.jabber.org/streams" 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";
the associated class is "format". the associated class is "format".
o <nonmatching-hosts/> -- the hostname provided in a 'from' address o <nonmatching-hosts/> -- the hostname provided in a 'from' address
does not match the hostname (or any validated domain) negotiated does not match the hostname (or any validated domain) negotiated
via SASL or dialback; the associated class is "address". via SASL or dialback; the associated class is "address".
o <not-authorized/> -- the entity does not possess sufficient o <not-authorized/> -- the entity does not possess sufficient
privilegs to perform the desired action; the associated class is privileges to perform the desired action; the associated class is
"access". "access".
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; the associated class is "server". or authorization; the associated class is "server".
o <resource-constraint/> -- the server is resource-contrained and is o <resource-constraint/> -- the server is resource-contrained and is
unable to service the stream; the associated class is "server". unable to service the stream; the associated class is "server".
o <see-other-host/> -- the server will not provide service to the o <see-other-host/> -- the server will not provide service to the
skipping to change at page 18, line 21 skipping to change at page 18, line 21
version='1.0'> version='1.0'>
S: <?xml version='1.0'?> S: <?xml version='1.0'?>
<stream:stream <stream:stream
from='shakespeare.lit' from='shakespeare.lit'
id='id_123456789' id='id_123456789'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
... authentication ... ... authentication ...
C: <message><body>Bad XML, no closing body tag!</message> C: <message><body>Bad XML, no closing body tag!</message>
S: <stream:error class='client'> S: <stream:error class='format'>
<condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'> <condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'>
<xml-not-well-formed/> <xml-not-well-formed/>
</condition> </condition>
</stream:error> </stream:error>
S: </stream:stream> S: </stream:stream>
5. Stream Encryption 5. Stream Encryption
5.1 Overview 5.1 Overview
XMPP includes a method for securing the stream from tampering and XMPP includes a method for securing the stream from tampering and
eavesdropping. This channel encryption method makes use of the eavesdropping. This channel encryption method makes use of the
Transport Layer Security (TLS) [13] protocol, along with a "STARTTLS" Transport Layer Security (TLS) [13] protocol, along with a "STARTTLS"
extension that is modelled on similar extensions for the IMAP [26], extension that is modelled after similar extensions for the IMAP
POP3 [27], and ACAP [28] protocols as described in RFC 2595 [29]. The [26], POP3 [27], and ACAP [28] protocols as described in RFC 2595
namespace identifier for the STARTTLS extension is [29]. The namespace name for the STARTTLS extension is
'urn:ietf:params:xml:ns:xmpp-tls'. 'urn:ietf:params:xml:ns:xmpp-tls', which adheres to the format
defined in The IETF XML Registry [25].)
TLS SHOULD be used between any initiating entity and any receiving TLS SHOULD be used between any initiating entity and any receiving
entity (e.g., a stream from a client to a server or from one server entity (e.g., a stream from a client to a server or from one server
to another). An administrator of a given domain MAY require use of to another). An administrator of a given domain MAY require use of
TLS for either or both client-to-server communications and TLS for either or both client-to-server communications and
server-to-server communications. Servers SHOULD use TLS betweeen two server-to-server communications. Servers SHOULD use TLS betweeen two
domains for the purpose of securing server-to-server communcations. domains for the purpose of securing server-to-server communications.
When the remote domain is already known, the server can verify the When the remote domain is already known, the server can verify the
credentials of the known domain by comparing known keys or credentials of the known domain by comparing known keys or
certificates. When the remote domain is not recognized, it may still certificates. When the remote domain is not recognized, it may still
be possible to verify a certificate if it is signed by a common be possible to verify a certificate if it is signed by a common
trusted authority. Even if there is no way to verify certificates trusted authority. Even if there is no way to verify certificates
(e.g., an unknown domain with a self-signed certificate, or a (e.g., an unknown domain with a self-signed certificate, or a
certificate signed by an unrecognized authority), if the servers certificate signed by an unrecognized authority), if the servers
choose to communicate despite the lack of verified credentials, TLS choose to communicate despite the lack of verified credentials, TLS
still SHOULD be used to provide encryption. still SHOULD be used to provide channel encryption.
The following business rules apply: The following business rules apply:
1. An initiating entity that complies with this specification MUST 1. An initiating entity that complies with this specification MUST
include the "version='1.0'" flag in the initiating stream header. include the "version='1.0'" flag in the initiating stream header.
2. When a receiving entity that complies with this specification 2. When a receiving entity that complies with this specification
receives an initiating stream header that includes the receives an initiating stream header that includes the
"version='1.0'" flag, after sending a stream header in reply it "version='1.0'" flag, after sending a stream header in reply
MUST also send a <starttls/> element scoped by the (including the version flag) it MUST include a <starttls/>
'urn:ietf:params:xml:ns:xmpp-tls' namespace as well as the list element scoped by the 'urn:ietf:params:xml:ns:xmpp-tls' namespace
of other stream features it supports. with the list of other stream features it supports.
3. If the initiating entity chooses to use TLS for stream 3. If the initiating entity chooses to use TLS for stream
encryption, TLS negotiation MUST be completed before proceeding encryption, TLS negotiation MUST be completed before proceeding
to SASL negotiation. to SASL negotiation.
4. The initiating entity MUST validate the certificate presented by 4. The initiating entity MUST validate the certificate presented by
the receiving entity: the receiving entity:
Case 1 -- The initiating entity has been configured with a set of Case 1 -- The initiating entity has been configured with a set of
trusted root certificates: Normal certificate validation trusted root certificates: Normal certificate validation
skipping to change at page 21, line 8 skipping to change at page 21, line 8
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='1.0'" flag. entity, including the "version='1.0'" flag.
2. The receiving entity responds by opening a TCP connection and 2. The receiving entity responds by opening a TCP connection and
sending an XML stream header to the initiating entity. sending an XML stream header to the initiating entity, including
the "version='1.0'" flag.
3. The receiving entity offers the STARTTLS extension to the 3. The receiving entity offers the STARTTLS extension to the
initiating entity by sending it along with the list of supported initiating entity by including it with the list of other
stream features. supported stream features (if TLS is required for interaction
with the receiving entity, it SHOULD signal that fact by
including a <required/> element as a child of the <starttls/>
element).
4. The initiating entity issues the STARTTLS command to instruct the 4. The initiating entity issues the STARTTLS command to instruct the
receiving entity that it wishes to begin a TLS negotiation to receiving entity that it wishes to begin a TLS negotiation to
secure the stream. secure the stream.
5. The receiving entity MUST reply with either a <proceed/> element 5. The receiving entity MUST reply with either a <proceed/> element
or a <failure/> element scoped by the or a <failure/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace, but keep the 'urn:ietf:params:xml:ns:xmpp-tls' namespace. If the failure case
underlying TCP connection open. occurs, the receiving entity MUST terminate both the XML stream
and the underlying TCP connection. If the proceed case occurs,
the receiving entity MUST ignore any further XML data sent over
the XML stream but keep the underlying TCP connection open for
the purpose of completing the TLS negotiation.
6. The initiating entity begins a TLS negotiation in accordance with 6. The initiating entity and receiving entity attempt to complete a
RFC 2246 [13]. Upon completion of the negotiation, the initiating TLS negotiation in accordance with RFC 2246 [13].
entity initiates a new stream by sending a new opening XML stream
header to the receiving entity.
7. The receiving entity responds by sending an XML stream header to 7. If the TLS negotiation is successful, the initiating entity
the initiating entity along with the remaining available features SHOULD initiate a new stream by sending an opening XML stream
(but NOT including the STARTTLS element). header to the receiving entity. If the TLS negotiation is
unsuccessful, the receiving entity MUST terminate the TCP
connection.
8. Upon receiving the new stream header from the initiating entity,
the receiving entity SHOULD respond by sending a new XML stream
header to the initiating entity along with the remaining
available features (but NOT including the STARTTLS element).
5.3 Client-to-Server Example 5.3 Client-to-Server Example
The following example shows the data flow for a client securing a The following example shows the data flow for a client securing a
stream using STARTTLS (the IANA registers port 5222 for stream using STARTTLS (the IANA registers port 5222 for
client-to-server communications using XMPP/Jabber, but another port client-to-server communications using XMPP/Jabber, but another port
MAY be used). MAY be used).
Step 1: Client initiates stream to server: Step 1: Client initiates stream to server:
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client-to-server communications using XMPP/Jabber, but another port client-to-server communications using XMPP/Jabber, but another port
MAY be used). MAY be used).
Step 1: Client initiates stream to server: Step 1: Client initiates stream to server:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
to='capulet.com' to='capulet.com'
version='1.0'> version='1.0'>
Step 2: Server responds by sending a stream tag to the client: Step 2: Server responds by sending a stream tag to the client:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
version='1.0'> version='1.0'>
Step 3: Server sends the STARTTLS extension to the client along with Step 3: Server sends the STARTTLS extension to the client along with
authentication mechanisms and any other stream features (if TLS is authentication mechanisms and any other stream features:
required for interaction with this server, the server SHOULD signal
that fact by including a <required/> element as a child of the
<starttls/> element):
<stream:features> <stream:features>
<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'>
<required/> <required/>
</starttls> </starttls>
<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 sends the STARTTLS command to the server: Step 4: Client sends the STARTTLS command to the server:
<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5: Server informs client to proceed: Step 5: Server informs client to proceed:
<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> <proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5 (alt): Server informs client that TLS negotiation has failed Step 5 (alt): Server informs client that TLS negotiation has failed
and closes stream: and closes both stream and TCP connection:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> <failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
</stream:stream> </stream:stream>
Step 6: Client and server complete TLS negotiation over the existing Step 6: Client and server attempt to complete TLS negotiation over
TCP connection. the existing TCP connection.
Step 7: Client initiates a new stream to the server: Step 7: If TLS negotiation is successful, client initiates a new
stream to the server:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
to='capulet.com' to='capulet.com'
version='1.0'> version='1.0'>
Step 7 (alt): If TLS negotiation is unsuccessful, server MUST close
TCP connection.
Step 8: Server responds by sending a stream header to the client Step 8: Server responds by sending a stream header to the client
along with any remaining negotiatiable stream features: along with any remaining negotiable stream features:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='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>
skipping to change at page 23, line 36 skipping to change at page 24, line 4
stream using STARTTLS (the IANA registers port 5269 for stream using STARTTLS (the IANA registers port 5269 for
server-to-server communications using XMPP/Jabber, but another port server-to-server communications using XMPP/Jabber, but another port
MAY be used). MAY be used).
Step 1: Server1 initiates stream to Server2: Step 1: Server1 initiates stream to Server2:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
Step 2: Server2 responds by sending a stream tag to Server1: Step 2: Server2 responds by sending a stream tag to Server1:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
version='1.0'> version='1.0'>
Step 3: Server2 sends the STARTTLS extension to Server1 along with Step 3: Server2 sends the STARTTLS extension to Server1 along with
authentication mechanisms and any other stream features (if TLS is authentication mechanisms and any other stream features:
required for interaction with Server2, it SHOULD signal that fact by
including a <required/> element as a child of the <starttls/>
element):
<stream:features> <stream:features>
<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
<required/> <required/>
</starttls> </starttls>
<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>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
skipping to change at page 24, line 34 skipping to change at page 24, line 39
Step 5: Server2 informs Server1 to proceed: Step 5: Server2 informs Server1 to proceed:
<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> <proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
Step 5 (alt): Server2 informs Server1 that TLS negotiation has failed Step 5 (alt): Server2 informs Server1 that TLS negotiation has failed
and closes stream: and closes stream:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> <failure xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
</stream:stream> </stream:stream>
Step 6: Server1 and Server2 complete TLS negotiation via TCP. Step 6: Server1 and Server2 attempt to complete TLS negotiation via
TCP.
Step 7: Server1 initiates a new stream to Server2: Step 7: If TLS negotiation is successful, Server1 initiates a new
stream to Server2:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
Step 7 (alt): If TLS negotiation is unsuccessful, server MUST close
TCP connection.
Step 8: Server2 responds by sending a stream header to Server1 along Step 8: Server2 responds by sending a stream header to Server1 along
with any remaining negotiatiable stream features: with any remaining negotiable stream features:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='12345678'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='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>
skipping to change at page 26, line 11 skipping to change at page 26, line 11
Step 9: Server1 SHOULD continue with stream authentication (Section Step 9: Server1 SHOULD continue with stream authentication (Section
6). 6).
6. Stream Authentication 6. Stream Authentication
XMPP includes two methods for enforcing authentication at the level XMPP includes two methods for enforcing authentication at the level
of XML streams. The secure and preferred method for authenticating of XML streams. The secure and preferred method for authenticating
streams between two entities uses an XMPP adaptation of the Simple streams between two entities uses an XMPP adaptation of the Simple
Authentication and Security Layer (SASL) [15]. If SASL negotiation is Authentication and Security Layer (SASL) [15]. If SASL negotiation is
not possible, some level of trust MAY be established based on not possible, some level of trust MAY be established between servers
existing trust in DNS; the authentication method used in this case is based on existing trust in DNS; the authentication method used in
the server dialback protocol that is native to XMPP (no such ad-hoc this case is the server dialback protocol that is native to XMPP (no
method is defined between a client and a server). If SASL is used for such ad-hoc method is defined between a client and a server). If SASL
server-to-server authentication, the servers MUST NOT use dialback. is used for server-to-server authentication, the servers MUST NOT use
For further information about the relative merits of these two dialback. For further information about the relative merits of these
methods, consult Security Considerations (Section 11). two methods, consult Security Considerations (Section 11).
Stream authentication is REQUIRED for all direct communications Stream authentication is REQUIRED for all direct communications
between two entities; if an entity sends a stanza to an between two entities; if an entity sends a stanza to an
unauthenticated stream, the receiving entity SHOULD silently drop the unauthenticated stream, the receiving entity SHOULD silently drop the
stanza and MUST NOT process it. stanza, MUST NOT process it, and MAY terminate both the XML stream
and the underlying TCP connection.
6.1 SASL Authentication 6.1 SASL Authentication
6.1.1 Overview 6.1.1 Overview
The Simple Authentication and Security Layer (SASL) provides a The Simple Authentication and Security Layer (SASL) provides a
generalized method for adding authentication support to generalized method for adding authentication support to
connection-based protocols. XMPP uses a generic XML namespace profile connection-based protocols. XMPP uses a generic XML namespace profile
for SASL that conforms to section 4 ("Profiling Requirements") of RFC for SASL that conforms to section 4 ("Profiling Requirements") of RFC
2222 [15] (the XMPP-specific namespace identifier is 2222 [15] (the XMPP-specific namespace name is
'urn:ietf:params:xml:ns:xmpp-sasl'). 'urn:ietf:params:xml:ns:xmpp-sasl'), which adheres to the format
defined in The IETF XML Registry [25].)
The following business rules apply: The following business rules apply:
1. If TLS is used for stream encryption, SASL MUST NOT be used for 1. If TLS is used for stream encryption, SASL SHOULD NOT be used for
anything but stream authentication (i.e., a security layer MUST anything except stream authentication (i.e., a security layer
NOT be negotiated using SASL). Conversely, if a security layer is SHOULD NOT be negotiated using SASL). Conversely, if a security
to be negotiated via SASL, TLS MUST NOT be used. layer is to be negotiated via SASL, TLS SHOULD NOT be used.
2. If the initiating entity is capable of authenticating via SASL, 2. If the initiating entity is capable of authenticating via SASL,
it it MUST include the "version='1.0'" flag in the initiating it MUST include the "version='1.0'" flag in the initiating stream
stream header. header.
3. If the receiving entity is capable of accepting authentications 3. If the receiving entity is capable of accepting authentications
via SASL, it MUST send one or more authentication mechanisms via SASL, it MUST send one or more authentication mechanisms
within a <mechanisms/> element scoped by the within a <mechanisms/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace in response to the 'urn:ietf:params:xml:ns:xmpp-sasl' namespace in response to the
opening stream tag received from the initiating entity. opening stream tag received from the initiating entity.
4. If the SASL negotiation involves negotiation of a security layer, 4. If the SASL negotiation involves negotiation of a security layer,
the receiving entity MUST discard any knowledge obtained from the the receiving entity MUST discard any knowledge obtained from the
initiating entity which was not obtained from the SASL initiating entity which was not obtained from the SASL
skipping to change at page 27, line 19 skipping to change at page 27, line 21
the initiating entity MUST discard any knowledge obtained from the initiating entity MUST discard any knowledge obtained from
the receiving entity which was not obtained from the SASL the receiving entity which was not obtained from the SASL
negotiation itself. negotiation itself.
The following syntax rules apply: The following syntax rules apply:
1. The initial challenge MUST include a realm, nonce, qop, charset, 1. The initial challenge MUST include a realm, nonce, qop, charset,
and algorithm. and algorithm.
2. The inital response for client-to-server negotiation MUST include 2. The inital response for client-to-server negotiation MUST include
a username, realm, nonce, cnonce, nc, qop, digest-uri, response, all and only a username, realm, nonce, cnonce, nc, qop,
charset, and authzid. digest-uri, response, charset, and authzid.
3. The inital response for server-to-server negotiation MUST include 3. The inital response for server-to-server negotiation MUST include
a realm, nonce, cnonce, nc, qop, digest-uri, response, and all and only a realm, nonce, cnonce, nc, qop, digest-uri,
charset. response, and charset.
4. The realm-value MUST be no more than 1023 bytes in length and 4. The realm-value MUST be no more than 1023 bytes in length and
MUST conform to the nameprep [8] profile of stringprep [9]. MUST conform to the nameprep [8] profile of stringprep [9].
5. The username-value MUST be no more than 1023 bytes in length and 5. The username-value MUST be no more than 1023 bytes in length and
MUST conform to the nodeprep [10] profile of stringprep [9]. MUST conform to the nodeprep [10] profile of stringprep [9].
6. The response-value MUST be computed in accordance with the 6. The response-value MUST be computed in accordance with the
relevant SASL mechanism as defined by the appropriate RFC (e.g., relevant SASL mechanism as defined by the appropriate RFC (e.g.,
RFC 2831 [16] for digest authentication). RFC 2831 [16] for digest authentication).
7. The resource identifier portion of the authzid-value MUST be no 7. The authzid-value MUST be a Jabber Identifier of the form
more than 1023 bytes in length and MUST conform to the <user@domain/resource>, i.e., it MUST include a node identifier,
resourceprep [11] profile of stringprep [9]. domain identifier, and resource identifier.
6.1.2 Narrative 6.1.2 Narrative
When an initiating entity authenticates with a receiving entity, the When an initiating entity authenticates with a receiving entity, the
steps involved are as follows: steps involved are as follows:
1. The initiating entity requests SASL authentication by including a 1. The initiating entity requests SASL authentication by including a
'version' attribute in the opening XML stream header sent to the 'version' attribute in the opening XML stream header sent to the
receiving entity, with the value set to "1.0". receiving entity, with the value set to "1.0".
2. After sending an XML stream header in response, the receiving 2. After sending an XML stream header in response, the receiving
entity sends a list of available SASL authentication mechanisms, entity sends a list of available SASL authentication mechanisms;
each of which is a <mechanism/> element included as a child each of these is a <mechanism/> element included as a child
within a <mechanisms/> container element scoped by the within a <mechanisms/> container element scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace that is sent as a 'urn:ietf:params:xml:ns:xmpp-sasl' namespace, 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
channel encryption must be established before a particular channel encryption must be established before a particular
authentication mechanism may be used, the receiving entity MUST authentication mechanism may be used, the receiving entity MUST
NOT provide that mechanism in the list of available SASL NOT provide that mechanism in the list of available SASL
authentication methods. If the initiating entity presents a valid authentication methods prior to channel encryption. If the
initiating entity certificate during TLS negotiation, the initiating entity presents a valid initiating entity certificate
receiving entity MAY offer the SASL EXTERNAL mechanism to the during prior TLS negotiation, the receiving entity MAY offer the
initiating entity during stream authentication (see RFC 2222 SASL EXTERNAL mechanism to the initiating entity during stream
[15]). authentication (see RFC 2222 [15]).
3. The initiating entity selects a mechanism by sending an <auth/> 3. The initiating entity selects a mechanism by sending an <auth/>
element scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl' element scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl'
namespace to the receiving entity; this element MAY optionally namespace to the receiving entity and including the appropriate
value for the 'mechanism' attribute; this element MAY optionally
contain character data (in SASL terminology the "initial contain character data (in SASL terminology the "initial
response") if the mechanism supports or requires it. If the response") if the mechanism supports or requires it. If the
initiating entity selects the EXTERNAL mechanism for initiating entity selects the EXTERNAL mechanism for
authentication, the authentication credentials shall be taken authentication, the authentication credentials shall be taken
from the certificate presented during TLS negotiation. from the certificate presented during prior TLS negotiation.
4. If necessary, the receiving entity challenges the initiating 4. If necessary, the receiving entity challenges the initiating
entity by sending a <challenge/> element scoped by the entity by sending a <challenge/> element scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (which entity; this element MAY optionally contain character data (which
MUST be computed in accordance with the SASL mechanism chosen by MUST be computed in accordance with the SASL mechanism chosen by
the initiating entity). the initiating entity).
5. The initiating entity responds to the challenge by sending a 5. The initiating entity responds to the challenge by sending a
<response/> element scoped by the <response/> element scoped by the
skipping to change at page 30, line 5 skipping to change at page 30, line 5
exchange sequence: Challenges and responses are carried through the exchange sequence: Challenges and responses are carried through the
exchange of <challenge/> elements from receiving entity to exchange of <challenge/> elements from receiving entity to
initiating entity and <response/> elements from initiating entity initiating entity and <response/> elements from initiating entity
to receiving entity. The receiving entity reports failure by to receiving entity. The receiving entity reports failure by
sending a <failure/> element and success by sending a <success/> sending a <failure/> element and success by sending a <success/>
element; the initiating entity aborts the exchange by sending an element; the initiating entity aborts the exchange by sending an
<abort/> element. (All of these elements are scoped by the <abort/> element. (All of these elements are scoped by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace.) 'urn:ietf:params:xml:ns:xmpp-sasl' namespace.)
security layer negotiation: If a security layer is negotiated, both security layer negotiation: If a security layer is negotiated, both
sides consider the original stream closed and new <stream/> sides consider the original stream closed and new <stream> headers
headers are sent by both entities. The security layer takes effect are sent by both entities. The security layer takes effect
immediately following the ">" character of the <response/> element immediately following the ">" character of the <response/> element
for the client and immediately following the closing ">" character for the client and immediately following the closing ">" character
of the <succeed/> element for the server. (Both of these elements of the <succeed/> element for the server. (Both of these elements
are scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl' namespace.) are scoped by the 'urn:ietf:params:xml:ns:xmpp-sasl' namespace.)
use of the authorization identity: The authorization identity is used use of the authorization identity: The authorization identity is used
by xmpp only in negotiation between a client and a server, and by xmpp only in negotiation between a client and a server, and
denotes the "full JID" (user@domain/resource) requested by the denotes the "full JID" (user@domain/resource) requested by the
user or application associated with the client. user or application associated with the client.
skipping to change at page 36, line 23 skipping to change at page 36, line 23
Receiving Server. Receiving Server.
3. Receiving Server establishes a connection to Authoritative 3. Receiving Server establishes a connection to Authoritative
Server. Server.
4. Receiving Server sends the same 'key' value to Authoritative 4. Receiving Server sends the same 'key' value to Authoritative
Server. Server.
5. Authoritative Server replies that key is valid or invalid. 5. Authoritative Server replies that key is valid or invalid.
6. Receiving Server tells Originating Server whether it is 6. Receiving Server informs Originating Server whether it is
authenticated or not. authenticated or not.
We can represent this flow of events graphically as follows: We can represent this flow of events graphically as follows:
Originating Receiving Originating Receiving
Server Server Server Server
----------- --------- ----------- ---------
| | | |
| establish connection | | establish connection |
| ----------------------> | | ----------------------> |
skipping to change at page 39, line 51 skipping to change at page 39, line 51
<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 and shared secret Server in Step 4. Based on this information as well as shared
information within the Authoritative Server's network, the key secret information within the Authoritative Server's network,
is verified. Any verifiable method MAY be used to generate the the key is verified. Any verifiable method MAY be used to
key. If the value of the 'to' address does not match a hostname generate the key. If the value of the 'to' address does not
recognized by Authoritative Server, then Authoritative Server match a hostname recognized by Authoritative Server, then
MUST generate a <host-unknown/> stream error condition and Authoritative Server MUST generate a <host-unknown/> stream
terminate both the XML stream and the underlying TCP connection. error condition and terminate both the XML stream and the
If the value of the 'from' address does not match the hostname underlying TCP connection. If the value of the 'from' address
represented by Receiving Server when opening the TCP connection does not match the hostname represented by Receiving Server when
(or any validated domain), then Authoritative Server MUST opening the TCP connection (or any validated domain), then
generate a <nonmatching-hosts/> stream error condition and Authoritative Server MUST generate a <nonmatching-hosts/> stream
terminate both the XML stream and the underlying TCP connection. error condition and terminate both the XML stream and the
underlying TCP connection.
9. Authoritative Server sends a stanza back to Receiving Server 9. Authoritative Server sends a stanza back to Receiving Server
verifying whether the key was valid or invalid: verifying whether the key was valid or invalid:
<db:verify <db:verify
from='Originating Server' from='Originating Server'
to='Receiving Server' to='Receiving Server'
type='valid' type='valid'
id='457F9224A0...'/> id='457F9224A0...'/>
skipping to change at page 41, line 25 skipping to change at page 41, line 25
Receiving Server; before that, all data stanzas sent to Receiving Server; before that, all data stanzas sent to
Receiving Server SHOULD be silently dropped. Receiving Server SHOULD be silently dropped.
Even if dialback negotiation is successful, a server MUST verify that Even if dialback negotiation is successful, a server MUST verify that
all XML stanzas received from the other server include a 'from' all XML stanzas received from the other server include a 'from'
attribute and a 'to' attribute; if a stanza does not meet this attribute and a 'to' attribute; if a stanza does not meet this
restriction, the server that receives the stanza MUST generate an restriction, the server that receives the stanza MUST generate an
<invalid-xml/> stream error condition and terminate both the XML <invalid-xml/> stream error condition and terminate both the XML
stream and the underlying TCP connection. Furthermore, a server MUST stream and the underlying TCP connection. Furthermore, a server MUST
verify that the 'from' attribute of stanzas received from the other verify that the 'from' attribute of stanzas received from the other
server includes the validated domain (or any validated domain); if a server includes a validated domain for the stream; if a stanza does
stanza does not meet this restriction, the server that receives the not meet this restriction, the server that receives the stanza MUST
stanza MUST generate a <nonmatching-hosts/> stream error condition generate a <nonmatching-hosts/> stream error condition and terminate
and terminate both the XML stream and the underlying TCP connection. both the XML stream and the underlying TCP connection. Both of these
Both of these checks help to prevent spoofing related to particular checks help to prevent spoofing related to particular stanzas.
stanzas.
7. XML Stanzas 7. XML Stanzas
7.1 Overview 7.1 Overview
Once the XML streams in each direction have been authenticated and Once the XML streams in each direction have been authenticated and
(if desired) encrypted, XML stanzas can be sent over the streams. (if desired) encrypted, XML stanzas can be sent over the streams.
Three XML stanza types are defined for the 'jabber:client' and Three XML stanza types are defined for the 'jabber:client' and
'jabber:server' namespaces: <message/>, <presence/>, and <iq/>. 'jabber:server' namespaces: <message/>, <presence/>, and <iq/>.
skipping to change at page 42, line 25 skipping to change at page 42, line 25
mechanism whereby one entity pushes information to another entity, mechanism whereby one entity pushes information to another entity,
similar to the communications that occur in a system such as email. similar to the communications that occur in a system such as email.
The <presence/> element can be seen as a basic broadcast or The <presence/> element can be seen as a basic broadcast or
"publish-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. The <iq/> element can be seen as a which they have subscribed. The <iq/> element can be seen as a
"request-response" mechanism similar to HTTP, whereby two entities "request-response" mechanism similar to HTTP, whereby two entities
can engage in a structured conversation using 'get' or 'set' requests can engage in a structured conversation using 'get' or 'set' requests
and 'result' or 'error' responses. and 'result' or 'error' responses.
The syntax for these stanza types is defined below.
7.2 Common Attributes 7.2 Common Attributes
Five attributes are common to message, presence, and IQ stanzas. The following five attributes are common to message, presence, and IQ
These are defined below. stanzas:
7.2.1 to 7.2.1 to
The 'to' attribute specifies the JID of the intended recipient for The 'to' attribute specifies the JID of the intended recipient for
the stanza. the stanza.
In the 'jabber:client' namespace, a stanza SHOULD possess a 'to' In the 'jabber:client' namespace, a stanza SHOULD possess a 'to'
attribute, although a stanza sent from a client to a server for attribute, although a stanza sent from a client to a server for
handling by that server (e.g., presence sent to the server for handling by that server (e.g., presence sent to the server for
broadcasting to other entities) MAY legitimately lack a 'to' broadcasting to other entities) MAY legitimately lack a 'to'
skipping to change at page 43, line 32 skipping to change at page 43, line 29
contained in the 'from' attribute MUST match the hostname of the contained in the 'from' attribute MUST match the hostname of the
sending server (or any validated domain) as communicated in the SASL sending server (or any validated domain) as communicated in the SASL
negotiation or dialback negotiation; if a server receives a stanza negotiation or dialback negotiation; if a server receives a stanza
that does not meet this restriction, it MUST generate a that does not meet this restriction, it MUST generate a
<nonmatching-hosts/> stream error condition. Both of these conditions <nonmatching-hosts/> stream error condition. Both of these conditions
MUST result in closing of the stream and termination of the MUST result in closing of the stream and termination of the
underlying TCP connection. underlying TCP connection.
7.2.3 id 7.2.3 id
The optional 'id' attribute MAY be used to track stanzas sent and The optional 'id' attribute MAY be used by a sending entity for
received. The 'id' attribute is generated by the sender. An 'id' internal tracking of stanzas that it sends and receives (especially
attribute included in an IQ request of type "get" or "set" SHOULD be for tracking the request-response interaction inherent in the use of
returned to the sender in any IQ response of type "result" or "error" IQ stanzas). If the stanza sent by the sending entity is an IQ stanza
generated by the recipient of the request. A recipient of a message of type "get" or "set", the receiving entity MUST include an 'id'
or presence stanza MAY return that 'id' in any replies, but is NOT attribute with the same value in any replies of type "result" or
REQUIRED to do so. "error". The value of the 'id' attribute is NOT REQUIRED to be unique
either globally, within a domain, or within a stream.
The value of the 'id' attribute is not intended to be unique --
globally, within a domain, or within a stream. It is generated by a
sender only for internal tracking of information within the sending
application.
7.2.4 type 7.2.4 type
The 'type' attribute specifies detailed information about the purpose The 'type' attribute specifies detailed information about the purpose
or context of the message, presence, or IQ stanza. The particular or context of the message, presence, or IQ stanza. The particular
allowable values for the 'type' attribute vary depending on whether allowable values for the 'type' attribute vary depending on whether
the stanza is a message, presence, or IQ, and thus are specified in the stanza is a message, presence, or IQ, and thus are defined in the
the following sections. following sections.
7.2.5 xml:lang 7.2.5 xml:lang
Any message or presence stanza MAY possess an 'xml:lang' attribute as A stanza SHOULD possess an 'xml:lang' attribute (as defined in
defined in Section 2.12 of the XML specification [1]. Ths value this Section 2.12 of the XML specification [1]) specifying the default
attribute specifies the default language of any XML character data language of any XML character data contained in the stanza or its
contained in the stanza or its child elements. An IQ stanza SHOULD child elements. The value of the 'xml:lang' attribute MUST be an
NOT possess an 'xml:lang' attribute, since it is merely a vessel for NMTOKEN and MUST conform to the format defined in RFC 3066 [17].
data in other namespaces and does not itself contain children that
have CDATA. The value of the 'xml:lang' attribute MUST be an NMTOKEN
and MUST conform to the format defined in RFC 3066 [17].
7.3 Message Stanzas 7.3 Message Stanzas
Message stanzas in the 'jabber:client' or 'jabber:server' namespace Message stanzas in the 'jabber:client' or 'jabber:server' namespace
are used to "push" information to another entity. Common uses in the are used to "push" information to another entity. Common uses in the
context of instant messaging include single messages, messages sent context of instant messaging include single messages, messages sent
in the context of a chat conversation, messages sent in the context in the context of a chat conversation, messages sent in the context
of a multi-user chat room, headlines, and errors. These messages of a multi-user chat room, headlines, and errors. These messages
types are identified more fully below. types are identified more fully below.
skipping to change at page 44, line 47 skipping to change at page 44, line 37
o groupchat o groupchat
o headline o headline
For information about the meaning of these message types, refer to For information about the meaning of these message types, refer to
XMPP IM [23]. XMPP IM [23].
7.3.2 Children 7.3.2 Children
As described under extended namespaces (Section 7.6), a message As described under extended namespaces (Section 7.6), a message
stanza MAY contain any properly-namespaced child element as long as stanza MAY contain any properly-namespaced child element.
the namespace name is not "jabber:client", "jabber:server", or
"http://etherx.jabber.org/streams".
In accordance with the default namespace declaration, by default a In accordance with the default namespace declaration, by default a
message stanza is in the 'jabber:client' or 'jabber:server' message stanza is in the 'jabber:client' or 'jabber:server'
namespace, which defines certain allowable children of message namespace, which defines certain allowable children of message
stanzas. If the message stanza is of type "error", it MUST include an stanzas. If the message stanza is of type "error", it MUST include an
<error/> child; for details, see Section 7.7. If the message stanza <error/> child; for details, see Section 7.7. If the message stanza
has no 'type' attribute or has a 'type' attribute with a value of has no 'type' attribute or has a 'type' attribute with a value of
"chat", "groupchat", or "headline", it MAY contain any of the "chat", "groupchat", or "headline", it MAY contain any of the
following child elements without an explicit namespace declaration: following child elements without an explicit namespace declaration:
7.3.2.1 Body 7.3.2.1 Subject
The <body/> element contains the textual contents of the message;
normally included but NOT REQUIRED. The <body/> element SHOULD NOT
possess any attributes, with the exception of the 'xml:lang'
attribute. Multiple instances of the <body/> element MAY be included
but only if each instance possesses an 'xml:lang' attribute with a
distinct language value. The <body> element MUST NOT contain mixed
content.
7.3.2.2 Subject
The <subject/> element specifies the topic of the message. The The <subject/> element specifies the topic of the message. The
<subject/> element SHOULD NOT possess any attributes, with the <subject/> element SHOULD NOT possess any attributes, with the
exception of the 'xml:lang' attribute. Multiple instances of the exception of the 'xml:lang' attribute. Multiple instances of the
<subject/> element MAY be included for the purpose of providing <subject/> element MAY be included for the purpose of providing
alternate versions of the same subject, but only if each instance alternate versions of the same subject, but only if each instance
possesses an 'xml:lang' attribute with a distinct language value. The possesses an 'xml:lang' attribute with a distinct language value. The
<subject> element MUST NOT contain mixed content. <subject> element MUST NOT contain mixed content.
7.3.2.2 Body
The <body/> element contains the textual contents of the message;
this child element is normally included but NOT REQUIRED. The <body/>
element SHOULD NOT possess any attributes, with the exception of the
'xml:lang' attribute. Multiple instances of the <body/> element MAY
be included but only if each instance possesses an 'xml:lang'
attribute with a distinct language value. The <body> element MUST NOT
contain mixed content.
7.3.2.3 Thread 7.3.2.3 Thread
The <thread/> element contains a random string that is generated by The <thread/> element contains a random string that is generated by
the sender and that SHOULD be copied back in replies; it is used for the sender and that SHOULD be copied back in replies; it is used for
tracking a conversation thread (sometimes referred to as an "IM tracking a conversation thread (sometimes referred to as an "IM
session") between two entities. If used, it MUST be unique to that session") between two entities. If used, it MUST be unique to that
conversation thread within the stream and MUST be consistent conversation thread within the stream and MUST be consistent
throughout that conversation. The use of the <thread/> element is throughout that conversation. The use of the <thread/> element is
optional and is not used to identify individual messages, only optional and is not used to identify individual messages, only
conversations. Only one <thread/> element MAY be included in a conversations. Only one <thread/> element MAY be included in a
message stanza, and it MUST NOT possess any attributes. The <thread/> message stanza, and it MUST NOT possess any attributes. The <thread/>
element MUST be treated as an opaque string by entities; no semantic element MUST be treated as an opaque string by entities; no semantic
meaning may be derived from it, and only exact, case-insensitve meaning may be derived from it, and only exact, case-insensitve
comparisons be made against it. The <thread> element MUST NOT contain comparisons may be made against it. The <thread> element MUST NOT
mixed content. contain mixed content.
The method for generating thread IDs SHOULD be as follows: The method for generating thread IDs SHOULD be as follows:
1. concatenate the sender's full JID (user@domain/resource) with the 1. concatenate the sender's full JID (user@domain/resource) with the
recipient's full JID recipient's full JID
2. concatenate these JID strings with a full ISO-8601 timestamp 2. concatenate these JID strings with a full ISO-8601 timestamp
including year, month, day, hours, minutes, seconds, and UTC including year, month, day, hours, minutes, seconds, and UTC
offset in the following format: yyyy-mm-dd-Thh:mm:ss-hh:mm offset in the following format: YYYY-MM-DD-Thh:mm:ssTZD (where
TZD is either "Z" for UTC or "[+|-]hh:mm" for an offset from UTC)
3. hash the resulting string according to the SHA1 algorithm 3. hash the resulting string according to the SHA1 algorithm
4. convert the hexidecimal SHA1 output to all lowercase 4. convert the hexidecimal SHA1 output to all lowercase
7.4 Presence Stanzas 7.4 Presence Stanzas
Presence stanzas are used in the 'jabber:client' or 'jabber:server' Presence stanzas are used in the 'jabber:client' or 'jabber:server'
namespace to express an entity's current availability status (offline namespace to express an entity's current availability status (offline
or online, along with various sub-states of the latter and optional or online, along with various sub-states of the latter and optional
skipping to change at page 47, line 6 skipping to change at page 46, line 46
o unsubscribed -- The subscription request has been denied or a o unsubscribed -- The subscription request has been denied or a
previously-granted subscription has been cancelled. previously-granted subscription has been cancelled.
o probe -- A request for an entity's current presence. In general o probe -- A request for an entity's current presence. In general
SHOULD NOT be sent by a client. SHOULD NOT be sent by a client.
o error -- An error has occurred regarding processing or delivery of o error -- An error has occurred regarding processing or delivery of
a previously-sent presence stanza. a previously-sent presence stanza.
Information about the subscription model used within XMPP can be Detailed information about presence semantics and about the
found in XMPP IM [23]. subscription model used within XMPP can be found in XMPP IM [23].
7.4.2 Children 7.4.2 Children
As described under extended namespaces (Section 7.6), a presence As described under extended namespaces (Section 7.6), a presence
stanza MAY contain any properly-namespaced child element as long as stanza MAY contain any properly-namespaced child element.
the namespace name is not "jabber:client", "jabber:server", or
"http://etherx.jabber.org/streams".
In accordance with the default namespace declaration, by default a In accordance with the default namespace declaration, by default a
presence stanza is in the 'jabber:client' or 'jabber:server' presence stanza is in the 'jabber:client' or 'jabber:server'
namespace, which defines certain allowable children of presence namespace, which defines certain allowable children of presence
stanzas. If the presence stanza is of type "error", it MUST include stanzas. If the presence stanza is of type "error", it MUST include
an <error/> child; for details, see Section 7.7. If the presence an <error/> child; for details, see Section 7.7. If the presence
stanza possesses no 'type' attribute, it MAY contain any of the stanza possesses no 'type' attribute, it MAY contain any of the
following child elements (note that the <status/> child MAY be sent following child elements (note that the <status/> child MAY be sent
in a presence stanza of type "unavailable" or, for historical in a presence stanza of type "unavailable" or, for historical
reasons, "subscribe"): reasons, "subscribe"):
7.4.2.1 Show 7.4.2.1 Show
The optional <show/> element specifies a particular availability The optional <show/> element specifies a particular availability
status of an entity or specific resource (if a <show/> element is not status of an entity or specific resource (if a <show/> element is not
provided, default availability is assumed (if a <show/> element is provided, default availability is assumed). Only one <show/> element
not provided, default availability is assumed)). Only one <show/> MAY be included in a presence stanza, and it SHOULD NOT possess any
element MAY be included in a presence stanza, and it SHOULD NOT attributes. The CDATA value SHOULD be one of the following (values
possess any attributes. The CDATA value SHOULD be one of the other than these four SHOULD be ignored; additional availability
following (values other than these four SHOULD be ignored; additional types could be defined through a properly-namespaced child element of
availability types could be defined through a properly-namespaced the presence stanza):
child element of the presence stanza):
o away o away
o chat o chat
o xa o xa
o dnd o dnd
For information about the meaning of these values, refer to XMPP IM For information about the meaning of these values, refer to XMPP IM
skipping to change at page 48, line 15 skipping to change at page 47, line 51
conjunction with the show element to provide a detailed description conjunction with the show element to provide a detailed description
of an availability state (e.g., "In a meeting"). The <status/> of an availability state (e.g., "In a meeting"). The <status/>
element SHOULD NOT possess any attributes, with the exception of the element SHOULD NOT possess any attributes, with the exception of the
'xml:lang' attribute. Multiple instances of the <status/> element MAY 'xml:lang' attribute. Multiple instances of the <status/> element MAY
be included but only if each instance possesses an 'xml:lang' be included but only if each instance possesses an 'xml:lang'
attribute with a distinct language value. attribute with a distinct language value.
7.4.2.3 Priority 7.4.2.3 Priority
The optional <priority/> element specifies the priority level of the The optional <priority/> element specifies the priority level of the
connected resource. The value may be any integer between -128 to 127. connected resource. The value may be any integer between -128 and
Only one <priority/> element MAY be included in a presence stanza, 127. Only one <priority/> element MAY be included in a presence
and it MUST NOT possess any attributes. For information regarding the stanza, and it MUST NOT possess any attributes. For information
use of priority values in stanza routing within IM applications, see regarding the semantics of priority values in stanza routing within
XMPP IM [23]. IM applications, see XMPP IM [23].
7.5 IQ Stanzas 7.5 IQ Stanzas
7.5.1 Overview 7.5.1 Overview
Info/Query, or IQ, is a request-response mechanism, similar in some Info/Query, or IQ, is a request-response mechanism, similar in some
ways to HTTP [31]. IQ stanzas in the 'jabber:client' or ways to HTTP [31]. IQ stanzas in the 'jabber:client' or
'jabber:server' namespace enable an entity to make a request of, and 'jabber:server' namespace enable an entity to make a request of, and
receive a response from, another entity. The data content of the receive a response from, another entity. The data content of the
request and response is defined by the namespace declaration of a request and response is defined by the namespace declaration of a
direct child element of the IQ element, and the interaction is direct child element of the IQ element, and the interaction is
tracked by the requesting entity through use of the 'id' attribute, tracked by the requesting entity through use of the 'id' attribute.
which responding entities SHOULD return in any response.
Most IQ interactions follow a common pattern of structured data Most IQ interactions follow a common pattern of structured data
exchange such as get/result or set/result (although an error may be exchange such as get/result or set/result (although an error may be
returned in response to a request if appropriate): returned in response to a request if appropriate):
Requesting Responding Requesting Responding
Entity Entity Entity Entity
---------- ---------- ---------- ----------
| | | |
| <iq type='get' id='1'> | | <iq type='get' id='1'> |
| ------------------------> | | ------------------------> |
| | | |
| <iq type='result' id='1'> | | <iq type='result' id='1'> |
| <------------------------ | | <------------------------ |
| | | |
| <iq type='set' id='2'> | | <iq type='set' id='2'> |
| ------------------------> | | ------------------------> |
| | | |
| <iq type='result' id='2'> | | <iq type='error' id='2'> |
| <------------------------ | | <------------------------ |
| | | |
An entity that receives an IQ request of type 'get' or 'set' MUST An entity that receives an IQ request of type "get" or "set" MUST
reply with an IQ response of type 'result' or 'error' (which response reply with an IQ response of type "result" or "error" (which response
MUST preserve the 'id' attribute of the request). An entity that MUST preserve the 'id' attribute of the request). An entity that
receives a stanza of type 'result' or 'error' MUST NOT respond to the receives a stanza of type "result" or "error" MUST NOT respond to the
stanza by sending a further IQ response of type 'result' or 'error'; stanza by sending a further IQ response of type "result" or "error";
however, as shown above, the requesting entity MAY send another however, as shown above, the requesting entity MAY send another
request (e.g., an IQ of type 'set' in order to provide required request (e.g., an IQ of type "set" in order to provide required
information discovered through a get/result pair). information discovered through a get/result pair).
7.5.2 Types of IQ 7.5.2 Types of IQ
The 'type' attribute of an IQ stanza is REQUIRED. The 'type' The 'type' attribute of an IQ stanza is REQUIRED. The 'type'
attribute specifies a distinct step within a request-response attribute specifies a distinct step within a request-response
interaction. The value SHOULD be one of the following (all other interaction. The value SHOULD be one of the following (all other
values SHOULD be ignored): values SHOULD be ignored):
o get -- The stanza is a request for information. o get -- The stanza is a request for information or requirements.
o set -- The stanza provides required data, sets new values, or o set -- The stanza provides required data, sets new values, or
replaces existing values. replaces existing values.
o result -- The stanza is a response to a successful get or set o result -- The stanza is a response to a successful get or set
request. request.
o error -- An error has occurred regarding processing or delivery of o error -- An error has occurred regarding processing or delivery of
a previously-sent get or set. a previously-sent get or set.
7.5.3 Children 7.5.3 Children
As described under extended namespaces (Section 7.6), an IQ stanza As described under extended namespaces (Section 7.6), an IQ stanza
MAY contain any properly-namespaced child element as long as the MAY contain any properly-namespaced child element. Note that an IQ
namespace name is not "jabber:client", "jabber"server", or "http:// stanza contains no children in the 'jabber:client' or 'jabber:server'
etherx.jabber.org/streams". However, an IQ stanza contains no namespace since it is a vessel for XML in another namespace.
children in the 'jabber:client' or 'jabber:server' namespace since it
is a vessel for XML in another namespace.
An IQ stanza of type "get" or "set" MUST include one and only one An IQ stanza of type "get" or "set" MUST include one and only one
child element. An the IQ stanza of type "error" SHOULD include the child element. An IQ stanza of type "error" SHOULD include the child
child element contained in the associated "set" or "get" and MUST element contained in the associated "set" or "get" and MUST include
include an <error/> child; for details, see Section 7.7. an <error/> child; for details, see Section 7.7.
7.6 Extended Namespaces 7.6 Extended Namespaces
While the core data elements in the "jabber:client" or While the core data elements in the "jabber:client" or
"jabber:server" namespace (along with their attributes and child "jabber:server" namespace (along with their attributes and child
elements) provide a basic level of functionality for messaging and elements) provide a basic level of functionality for messaging and
presence, XMPP uses XML namespaces to extend the core data elements presence, XMPP uses XML namespaces to extend the core data elements
for the purpose of providing additional functionality. Thus a for the purpose of providing additional functionality. Thus a
message, presence, or IQ stanza MAY house one or more optional child message, presence, or IQ stanza MAY house one or more optional child
elements containing content that extends the meaning of the message elements containing content that extends the meaning of the message
(e.g., an encrypted form of the message body). This child element MAY (e.g., an encrypted form of the message body). This child element MAY
be have any name and MUST possess an 'xmlns' namespace declaration have any name and MUST possess an 'xmlns' namespace declaration
(other than "jabber:client", "jabber:server", or "http:// (other than "jabber:client", "jabber:server", or "http://
etherx.jabber.org/streams") that defines all data contained within etherx.jabber.org/streams") that defines all data contained within
the child element. the child element.
Support for any given extended namespace is OPTIONAL on the part of Support for any given extended namespace is OPTIONAL on the part of
any implementation. If an entity does not understand such a any implementation. If an entity does not understand such a
namespace, the entity's expected behavior depends on whether the namespace, the entity's expected behavior depends on whether the
entity is (1) the recipient or (2) an entity that is routing the entity is (1) the recipient or (2) an entity that is routing the
stanza to the recipient. In particular: stanza to the recipient. In particular:
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associated application (if any). In particular: associated application (if any). In particular:
* If an entity receives a message or presence stanza that * If an entity receives a message or presence stanza that
contains XML data in an extended namespace it does not contains XML data in an extended namespace it does not
understand, the portion of the stanza that is in the unknown understand, the portion of the stanza that is in the unknown
namespace SHOULD be ignored. namespace SHOULD be ignored.
* If an entity receives a message stanza without a <body/> * If an entity receives a message stanza without a <body/>
element but containing only a child element bound by a element but containing only a child element bound by a
namespace it does not understand, it MUST ignore the entire namespace it does not understand, it MUST ignore the entire
stanza/ stanza.
* If an entity receives an IQ stanza in a namespace it does not * If an entity receives an IQ stanza in a namespace it does not
understand, the entity SHOULD return an IQ stanza of type understand, the entity SHOULD return an IQ stanza of type
"error" with an error condition of <feature-not-implemented/>. "error" with an error condition of <feature-not-implemented/>.
Router: If a routing entity (usually a server) handles a stanza that Router: If a routing entity (usually a server) handles a stanza that
contains a child element it does not understand, it SHOULD ignore contains a child element it does not understand, it SHOULD ignore
the associated XML data by passing it on untouched to the the associated XML data by passing it on untouched to the
recipient. recipient.
7.7 Stanza Errors 7.7 Stanza Errors
As defined herein, stanza-related errors are handled in a manner As defined herein, stanza-related errors are handled in a manner
similar to stream errors (Section 4.5). similar to stream errors (Section 4.5).
7.7.1 Rules 7.7.1 Rules
The following rules apply to stanza-related errors: The following rules apply to stanza-related errors:
o A stanza of type "error" MUST contain an <error/> child element. o A stanza whose 'type' attribute has a value of "error" MUST
contain an <error/> child element.
o The receiving or processing entity that returns an error to the o The receiving or processing entity that returns an error to the
sending entity SHOULD include the original XML sent along with the sending entity SHOULD include the original XML sent along with the
<error/> element and its children so that the sender can inspect <error/> element and its children so that the sender can inspect
and if necessary correct the XML before re-sending. and if necessary correct the XML before re-sending.
o An entity that receives a message stanza of type 'error' MUST NOT o An entity that receives a stanza whose 'type' attribute has a
respond to the stanza by sending a further message stanza of type value of "error" MUST NOT respond to the stanza with a further
'error'; this helps to prevent looping. stanza of type "error"; this helps to prevent looping.
o An <error/> child MUST NOT be included if the stanza type is o An <error/> child MUST NOT be included if the 'type' attribute has
something other than "error". a value other than "error".
7.7.2 Syntax 7.7.2 Syntax
The syntax for stanza-related errors is as follows: The syntax for stanza-related errors is as follows:
<stanza-name to='sender' type='error'> <stanza-name to='sender' type='error'>
[include sender XML here] [include sender XML here]
<error class='error-class'> <error class='error-class'>
<condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'> <condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
<descriptive-element-name/> <descriptive-element-name/>
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The stanza-name is one of message, presence, or iq. The stanza-name is one of message, presence, or iq.
The value of the 'class' attribute MUST be one of the following: The value of the 'class' attribute MUST be one of the following:
o access -- the condition relates to access rights, permissions, or o access -- the condition relates to access rights, permissions, or
authorization authorization
o address -- the condition relates to the JID or domain to which the o address -- the condition relates to the JID or domain to which the
stanza was addressed stanza was addressed
o app -- the condition is particular to an application and is
specified in a namespace other than
'urn:ietf:params:xml:ns:xmpp-stanzas'
o format -- the condition relates to XML format or structure o format -- the condition relates to XML format or structure
o recipient -- the condition relates to the state or capabilities of o recipient -- the condition relates to the state or capabilities of
the recipient (which may be the server) the recipient (which may be the server)
o server -- the condition relates to the internal state of the o server -- the condition relates to the internal state of the
server server
The <condition/> element MUST contain a child element that specifies The <condition/> element MUST contain a child element that specifies
a particular stanza-related error condition, as defined in the next a particular stanza-related error condition, and its namespace name
section. (Note: the XML namespace name MUST be 'urn:ietf:params:xml:ns:xmpp-stanzas', which adheres to the
'urn:ietf:params:xml:ns:xmpp-stanzas' that scopes the <condition/> format defined in The IETF XML Registry [25].
element adheres to the format defined in The IETF XML Registry [25].)
7.7.3 Conditions 7.7.3 Conditions
The following stanza-related error conditions are defined: The following stanza-related error conditions are defined:
o <bad-request/> -- the sender has sent XML that is malformed or o <bad-request/> -- the sender has sent XML that is malformed or
cannot be processed (e.g., a client-generated stanza includes a cannot be processed (e.g., a client-generated stanza includes a
'from' address, or an IQ stanza includes an unrecognized value of 'from' address, or an IQ stanza includes an unrecognized value of
the 'type' attribute); the associated class is "format". the 'type' attribute); the associated class is "format".
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implemented by the recipient or server and therefore cannot be implemented by the recipient or server and therefore cannot be
processed; the associated class is "recipient". processed; the associated class is "recipient".
o <forbidden/> -- the stanza is understood but the action is o <forbidden/> -- the stanza is understood but the action is
forbidden; the associated class is "access". forbidden; the associated class is "access".
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 class is "server". internal server error; the associated class is "server".
o <item-not-found/> -- the addressed JID or item requested cannot be
found; the associated class is "address".
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
Addressing (Section 3); the associated class is "address". Addressing (Section 3); the associated class is "address".
o <jid-not-found/> -- the value of the 'to' attribute in the
sender's stanza does not correspond to a Jabber ID on the user's
server or a remote server; the associated class is "address".
o <not-allowed/> -- the action is not permitted when attempted by o <not-allowed/> -- the action is not permitted when attempted by
the sender; the associated class is "access". the sender; the associated class is "access".
o <recipient-unavailable/> -- the specific recipient requested is o <recipient-unavailable/> -- the specific recipient requested is
currently unavailable; the associated class is "recipient". currently unavailable; the associated class is "recipient".
o <registration-required/> -- the user is not authorized to access o <registration-required/> -- the user is not authorized to access
the requested service because registration is required; the the requested service because registration is required; the
associated class is "access". associated class is "access".
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o <remote-server-timeout/> -- a remote server or service specified o <remote-server-timeout/> -- a remote server or service specified
as part or all of the JID of the intended recipient could not be as part or all of the JID of the intended recipient could not be
contacted within a reasonable amount of time; the associated class contacted within a reasonable amount of time; the associated class
is "server". is "server".
o <service-unavailable/> -- the service requested is currently o <service-unavailable/> -- the service requested is currently
unavailable on the server; the associated class is "server". unavailable on the server; the associated class is "server".
7.7.4 Extensibility 7.7.4 Extensibility
If desired, an XMPP application MAY provide custom error information; If desired, an XMPP application MAY provide custom error information
the error class MUST be "app" and the data MUST be contained in a by including a properly-namespaced child of the appropriate
properly-namespaced child of the <condition/> element (i.e., the descriptive element name, for example:
namespace name MUST NOT be one of namespace names defined herein).
<iq type='error' id='some-id'>
<error class='format'>
<condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
<bad-request>
<too-many-parameters xmlns='some-ns'/>
</bad-request>
</condition>
</error>
</iq>
8. XML Usage within XMPP 8. XML Usage within XMPP
8.1 Restrictions 8.1 Restrictions
XMPP is a simplified and specialized protocol for streaming XML XMPP is a simplified and specialized protocol for streaming XML
elements in order to exchange messages and presence information in elements in order to exchange messages and presence information in
close to real time. Because XMPP does not require the parsing of close to real time. Because XMPP does not require the parsing of
arbitrary and complete XML documents, there is no requirement that arbitrary and complete XML documents, there is no requirement that
XMPP must support the full XML specification [1]. In particular, the XMPP must support the full XML specification [1]. In particular, the
skipping to change at page 54, line 40 skipping to change at page 54, line 40
8.2 Namespaces 8.2 Namespaces
XML Namespaces [12] are used within all XMPP-compliant XML to create XML Namespaces [12] are used within all XMPP-compliant XML to create
strict boundaries of data ownership. The basic function of namespaces strict boundaries of data ownership. The basic function of namespaces
is to separate different vocabularies of XML elements that are is to separate different vocabularies of XML elements that are
structurally mixed together. Ensuring that XMPP-compliant XML is structurally mixed together. Ensuring that XMPP-compliant XML is
namespace-aware enables any XML to be structurally mixed with any namespace-aware enables any XML to be structurally mixed with any
data element within XMPP. data element within XMPP.
Additionally, XMPP is more strict about namespace prefixes than the Additionally, an XMPP implementation MAY be more strict about
XML namespace specification requires. namespace prefixes than the XML namespace specification requires.
8.3 Validation 8.3 Validation
Except as noted with regard to 'to' and 'from' addresses for stanzas Except as noted with regard to 'to' and 'from' addresses for stanzas
within the 'jabber:server' namespace, a server is not responsible for within the 'jabber:server' namespace, a server is not responsible for
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. Clients SHOULD NOT rely on the ability but is NOT REQUIRED to do so. Clients SHOULD NOT rely on the ability
to send data which does not conform to the schemas, and SHOULD ignore to send data which does not conform to the schemas, and SHOULD ignore
any non-conformant elements or attributes on the incoming XML stream. any non-conformant elements or attributes on the incoming XML stream.
skipping to change at page 58, line 7 skipping to change at page 58, line 7
9.5 Existing Registrations 9.5 Existing Registrations
The IANA registers "xmpp" as a GSSAPI [22] service name, as specified The IANA registers "xmpp" as a GSSAPI [22] service name, as specified
in Section 6.1.3. in Section 6.1.3.
Additionally, the IANA registers "jabber-client" and "jabber-server" Additionally, the IANA registers "jabber-client" and "jabber-server"
as keywords for TCP ports 5222 and 5269 respectively. as keywords for TCP ports 5222 and 5269 respectively.
10. Internationalization Considerations 10. Internationalization Considerations
Usage of the 'xml:lang' attribute is described above. If a client Each XML stanza SHOULD include the 'xml:lang' attribute as described
includes an 'xml:lang' attribute in a stanza, a server MUST NOT above. Servers MUST NOT modify or delete 'xml:lang' attributes from
modify or delete it. stanzas they receive from other entities.
11. Security Considerations 11. Security Considerations
11.1 High Security 11.1 High Security
For the purposes of XMPP communications (client-to-server and For the purposes of XMPP communications (client-to-server and
server-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.
Standalone, self-signed service certificates SHOULD NOT be used; Standalone, self-signed service certificates SHOULD NOT be used;
rather, an entity that wishes to generate a self-signed service rather, an entity that wishes to generate a self-signed service
certificate SHOULD first generate a self-signed Root CA certificate certificate SHOULD first generate a self-signed Root CA certificate
and then generate a signed service certificate. Entities that and then generate a signed service certificate. Entities that
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 the certificate rather than the service certificate; this avoids problems
problems associated with simple comparison of service certificates. associated with simple comparison of service certificates. If a
If a self-signed service certificate is used, an entity SHOULD NOT self-signed service certificate is used, an entity SHOULD NOT trust
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.
11.2 Client-to-Server Communications 11.2 Client-to-Server Communications
The TLS protocol for encrypting XML streams (defined under Section 5) The TLS protocol for encrypting XML streams (defined under Section 5)
provides a reliable mechanism for helping to ensure the provides a reliable mechanism for helping to ensure the
confidentiality and data integrity of data exchanged between two confidentiality and data integrity of data exchanged between two
entities. entities.
The SASL protocol for authenticating XML streams (defined under The SASL protocol for authenticating XML streams (defined under
Section 6.1) provides a reliable mechanism for validating that a Section 6.1) provides a reliable mechanism for validating that a
client connecting to a server is who it claims to be. client connecting to a server is who it claims to be.
The IP address and method of access of clients MUST NOT be made The IP address and method of access of clients MUST NOT be made
available by a server, nor are any connections other than the available by a server, nor are any connections other than the
original server connection required. This helps protect the client's original server connection required. This helps to protect the
server from direct attack or identification by third parties. client's server from direct attack or identification by third
parties.
End-to-end encryption of message bodies and presence status End-to-end encryption of message bodies and presence status
information MAY be effected through use of the methods defined in information MAY be effected through use of the methods defined in
End-to-End Object Encryption in XMPP [32]. End-to-End Object Encryption in XMPP [32].
11.3 Server-to-Server Communications 11.3 Server-to-Server Communications
A compliant implementation MUST support both TLS and SASL for 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 the lower-security Dialback implementation SHOULD also support the lower-security Dialback
Protocol (Section 6.2), which provides a mechanism for helping to Protocol (Section 6.2) as a fallback mechanism that helps to prevent
prevent the spoofing of domains. the spoofing of domains.
Because service provisioning is a matter of policy, it is OPTIONAL Because service provisioning is a matter of policy, it is OPTIONAL
for any given domain to communicate with other domains, and for any given domain to communicate with other domains, and
server-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. In the absence of communications, it SHOULD enable high security. In the absence of
high security, a domain MAY use server dialback for inter-domain high security, a domain MAY use server dialback for inter-domain
communications. communications.
Administrators may want to require use of SASL for server-to-server Administrators may want to require use of SASL for server-to-server
skipping to change at page 63, line 8 skipping to change at page 63, line 8
Technology - Universal Multiple-octet coded Character Set (UCS) Technology - Universal Multiple-octet coded Character Set (UCS)
- Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO - Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO
Standard 10646-1 Addendum 2, October 1996. Standard 10646-1 Addendum 2, October 1996.
[22] Linn, J., "Generic Security Service Application Program [22] Linn, J., "Generic Security Service Application Program
Interface, Version 2", RFC 2078, January 1997. Interface, Version 2", RFC 2078, January 1997.
Informative References Informative References
[23] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging [23] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging
(draft-ietf-xmpp-im-09, work in progress)", April 2003. (draft-ietf-xmpp-im-11, work in progress)", May 2003.
[24] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [24] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, August Resource Identifiers (URI): Generic Syntax", RFC 2396, August
1998, <http://www.ietf.org/rfc/rfc2396.txt>. 1998, <http://www.ietf.org/rfc/rfc2396.txt>.
[25] Mealling, M., "The IANA XML Registry", [25] Mealling, M., "The IANA XML Registry",
draft-mealling-iana-xmlns-registry-04 (work in progress), June draft-mealling-iana-xmlns-registry-04 (work in progress), June
2002. 2002.
[26] Crispin, M., "Internet Message Access Protocol - Version [26] Crispin, M., "Internet Message Access Protocol - Version
skipping to change at page 65, line 23 skipping to change at page 65, line 23
<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='qualified'> elementFormDefault='qualified'>
<xs:element name='stream'> <xs:element name='stream'>
<xs:complexType> <xs:complexType>
<xs:element ref='features' minOccurs='0' maxOccurs='1'/> <xs:element ref='features' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:choice> <xs:choice maxOccurs='1'>
<xs:any <xs:any namespace='jabber:client'/>
namespace='jabber:client' <xs:any namespace='jabber:server'/>
maxOccurs='1'/>
<xs:any
namespace='jabber:server'
maxOccurs='1'/>
</xs:choice> </xs:choice>
<xs:attribute name='to' type='xs:string' use='optional'/> <xs:attribute name='to' type='xs:string' use='optional'/>
<xs:attribute name='from' type='xs:string' use='optional'/> <xs:attribute name='from' type='xs:string' use='optional'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='version' type='xs:decimal' use='optional'/> <xs:attribute name='version' type='xs:decimal' use='optional'/>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='features'> <xs:element name='features'>
<xs:complexType> <xs:complexType>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='error'> <xs:element name='error'>
<xs:complexType> <xs:complexType>
<xs:any maxOccurs='1'
namespace='urn:ietf:params:xml:ns:xmpp-streams'/>
<xs:attribute name='class' use='required'/> <xs:attribute name='class' use='required'/>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='address'/> <xs:enumeration value='address'/>
<xs:enumeration value='app'/>
<xs:enumeration value='format'/> <xs:enumeration value='format'/>
<xs:enumeration value='redirect'/> <xs:enumeration value='redirect'/>
<xs:enumeration value='server'/> <xs:enumeration value='server'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
</xs:schema> </xs:schema>
skipping to change at page 66, line 28 skipping to change at page 66, line 25
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='urn:ietf:params:xml:ns:xmpp-tls' targetNamespace='urn:ietf:params:xml:ns:xmpp-tls'
xmlns='urn:ietf:params:xml:ns:xmpp-tls' xmlns='urn:ietf:params:xml:ns:xmpp-tls'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='starttls'> <xs:element name='starttls'>
<xs:complexType> <xs:complexType>
<xs:element ref='required' maxOccurs='1'> <xs:element
ref='required'
minOccurs='0'
maxOccurs='1'>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='proceed'/> <xs:element name='proceed'/>
<xs:element name='failure'/> <xs:element name='failure'/>
<xs:element name='required'/> <xs:element name='required'/>
</xs:schema> </xs:schema>
A.3 SASL namespace A.3 SASL namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
skipping to change at page 67, line 22 skipping to change at page 67, line 23
type='xs:string' use='optional'/> type='xs:string' use='optional'/>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='challenge' type='xs:string'/> <xs:element name='challenge' type='xs:string'/>
<xs:element name='response' type='xs:string'/> <xs:element name='response' type='xs:string'/>
<xs:element name='abort'/> <xs:element name='abort'/>
<xs:element name='success'/> <xs:element name='success'/>
<xs:element name='failure'> <xs:element name='failure'>
<xs:complexType> <xs:complexType>
<xs:choice> <xs:choice maxOccurs='1'>
<xs:element ref='invalid-realm' maxOccurs='1'> <xs:element ref='invalid-realm'/>
<xs:element ref='mechanism-too-weak' maxOccurs='1'> <xs:element ref='mechanism-too-weak'/>
<xs:element ref='not-authorized' maxOccurs='1'> <xs:element ref='not-authorized'/>
<xs:element ref='password-transition-required' maxOccurs='1'> <xs:element ref='password-transition-required'/>
<xs:element ref='temporary-auth-failure' maxOccurs='1'> <xs:element ref='temporary-auth-failure'/>
</xs:choice> </xs:choice>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='invalid-realm'/> <xs:element name='invalid-realm'/>
<xs:element name='mechanism-too-weak'/> <xs:element name='mechanism-too-weak'/>
<xs:element name='not-authorized'/> <xs:element name='not-authorized'/>
<xs:element name='password-transition-required'/> <xs:element name='password-transition-required'/>
<xs:element name='temporary-auth-failure'/> <xs:element name='temporary-auth-failure'/>
skipping to change at page 69, line 9 skipping to change at page 69, line 10
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='jabber:client' targetNamespace='jabber:client'
xmlns='jabber:client' xmlns='jabber:client'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='message'> <xs:element name='message'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:sequence>
<xs:element ref='body'
minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='subject' <xs:element ref='subject'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='body'
minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='thread' minOccurs='0' maxOccurs='1'/> <xs:element ref='thread' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
</xs:sequence>
<xs:attribute name='to' type='xs:string' use='optional'/> <xs:attribute name='to' type='xs:string' use='optional'/>
<xs:attribute name='from' type='xs:string' use='optional'/> <xs:attribute name='from' type='xs:string' use='optional'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xs:NMTOKEN' type='xs:NMTOKEN'
use='optional'/> use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='chat'/> <xs:enumeration value='chat'/>
skipping to change at page 70, line 16 skipping to change at page 70, line 17
<xs:attribute name='xml:lang' use='optional'/> <xs:attribute name='xml:lang' use='optional'/>
</xs:extension> </xs:extension>
</xs:simpleContent> </xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='thread' type='xs:string'/> <xs:element name='thread' type='xs:string'/>
<xs:element name='presence'> <xs:element name='presence'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:sequence>
<xs:element ref='show' minOccurs='0' maxOccurs='1'/> <xs:element ref='show' minOccurs='0' maxOccurs='1'/>
<xs:element ref='status' <xs:element ref='status'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='priority' minOccurs='0' maxOccurs='1'/> <xs:element ref='priority' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
</xs:sequence>
<xs:attribute name='to' type='xs:string' use='optional'/> <xs:attribute name='to' type='xs:string' use='optional'/>
<xs:attribute name='from' type='xs:string' use='optional'/> <xs:attribute name='from' type='xs:string' use='optional'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xs:NMTOKEN' type='xs:NMTOKEN'
use='optional'/> use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='subscribe'/> <xs:enumeration value='subscribe'/>
skipping to change at page 71, line 45 skipping to change at page 71, line 46
<xs:attribute name='type' use='required'> <xs:attribute name='type' use='required'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='get'/> <xs:enumeration value='get'/>
<xs:enumeration value='set'/> <xs:enumeration value='set'/>
<xs:enumeration value='result'/> <xs:enumeration value='result'/>
<xs:enumeration value='error'/> <xs:enumeration value='error'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
<xs:attribute name='xml:lang'
type='xs:NMTOKEN'
use='optional'/>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='error'> <xs:element name='error'>
<xs:complexType> <xs:complexType>
<xs:any maxOccurs='1'
namespace='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<xs:attribute name='class' use='required'/> <xs:attribute name='class' use='required'/>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='access'/> <xs:enumeration value='access'/>
<xs:enumeration value='address'/> <xs:enumeration value='address'/>
<xs:enumeration value='app'/>
<xs:enumeration value='format'/> <xs:enumeration value='format'/>
<xs:enumeration value='recipient'/> <xs:enumeration value='recipient'/>
<xs:enumeration value='server'/> <xs:enumeration value='server'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
</xs:schema> </xs:schema>
skipping to change at page 72, line 31 skipping to change at page 72, line 36
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='jabber:server' targetNamespace='jabber:server'
xmlns='jabber:server' xmlns='jabber:server'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='message'> <xs:element name='message'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:sequence>
<xs:element ref='body'
minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='subject' <xs:element ref='subject'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='body'
minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='thread' minOccurs='0' maxOccurs='1'/> <xs:element ref='thread' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
</xs:sequence>
<xs:attribute name='to' type='xs:string' use='required'/> <xs:attribute name='to' type='xs:string' use='required'/>
<xs:attribute name='from' type='xs:string' use='required'/> <xs:attribute name='from' type='xs:string' use='required'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xs:NMTOKEN' type='xs:NMTOKEN'
use='optional'/> use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='chat'/> <xs:enumeration value='chat'/>
skipping to change at page 73, line 39 skipping to change at page 73, line 44
<xs:attribute name='xml:lang' use='optional'/> <xs:attribute name='xml:lang' use='optional'/>
</xs:extension> </xs:extension>
</xs:simpleContent> </xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='thread' type='xs:string'/> <xs:element name='thread' type='xs:string'/>
<xs:element name='presence'> <xs:element name='presence'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='unbounded'> <xs:sequence>
<xs:element ref='show' minOccurs='0' maxOccurs='1'/> <xs:element ref='show' minOccurs='0' maxOccurs='1'/>
<xs:element ref='status' <xs:element ref='status'
minOccurs='0' maxOccurs='unbounded'/> minOccurs='0' maxOccurs='unbounded'/>
<xs:element ref='priority' minOccurs='0' maxOccurs='1'/> <xs:element ref='priority' minOccurs='0' maxOccurs='1'/>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
</xs:sequence>
<xs:attribute name='to' type='xs:string' use='required'/> <xs:attribute name='to' type='xs:string' use='required'/>
<xs:attribute name='from' type='xs:string' use='required'/> <xs:attribute name='from' type='xs:string' use='required'/>
<xs:attribute name='id' type='xs:ID' use='optional'/> <xs:attribute name='id' type='xs:ID' use='optional'/>
<xs:attribute name='xml:lang' <xs:attribute name='xml:lang'
type='xs:NMTOKEN' type='xs:NMTOKEN'
use='optional'/> use='optional'/>
<xs:attribute name='type' use='optional'> <xs:attribute name='type' use='optional'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='subscribe'/> <xs:enumeration value='subscribe'/>
skipping to change at page 75, line 20 skipping to change at page 75, line 25
<xs:attribute name='type' use='required'> <xs:attribute name='type' use='required'>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='get'/> <xs:enumeration value='get'/>
<xs:enumeration value='set'/> <xs:enumeration value='set'/>
<xs:enumeration value='result'/> <xs:enumeration value='result'/>
<xs:enumeration value='error'/> <xs:enumeration value='error'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
<xs:attribute name='xml:lang'
type='xs:NMTOKEN'
use='optional'/>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='error'> <xs:element name='error'>
<xs:complexType> <xs:complexType>
<xs:any maxOccurs='1'
namespace='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<xs:attribute name='class' use='required'/> <xs:attribute name='class' use='required'/>
<xs:simpleType> <xs:simpleType>
<xs:restriction base='xs:NCName'> <xs:restriction base='xs:NCName'>
<xs:enumeration value='access'/> <xs:enumeration value='access'/>
<xs:enumeration value='address'/> <xs:enumeration value='address'/>
<xs:enumeration value='app'/>
<xs:enumeration value='format'/> <xs:enumeration value='format'/>
<xs:enumeration value='recipient'/> <xs:enumeration value='recipient'/>
<xs:enumeration value='server'/> <xs:enumeration value='server'/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
</xs:schema> </xs:schema>
skipping to change at page 76, line 37 skipping to change at page 76, line 48
<xs:element name='host-gone'/> <xs:element name='host-gone'/>
<xs:element name='host-unknown'/> <xs:element name='host-unknown'/>
<xs:element name='internal-server-error'/> <xs:element name='internal-server-error'/>
<xs:element name='invalid-id'/> <xs:element name='invalid-id'/>
<xs:element name='invalid-namespace'/> <xs:element name='invalid-namespace'/>
<xs:element name='nonmatching-hosts'/> <xs:element name='nonmatching-hosts'/>
<xs:element name='not-authorized'/> <xs:element name='not-authorized'/>
<xs:element name='remote-connection-failed'/> <xs:element name='remote-connection-failed'/>
<xs:element name='resource-constraint'/> <xs:element name='resource-constraint'/>
<xs:element name='see-other-host'/> <xs:element name='see-other-host' type='xs:string'/>
<xs:element name='system-shutdown'/> <xs:element name='system-shutdown'/>
<xs:element name='unsupported-stanza-type'/> <xs:element name='unsupported-stanza-type'/>
<xs:element name='unsupported-version'/> <xs:element name='unsupported-version' type='xs:string'/>
<xs:element name='xml-not-well-formed'/> <xs:element name='xml-not-well-formed'/>
</xs:schema> </xs:schema>
A.8 Stanza error namespace A.8 Stanza error namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='urn:ietf:params:xml:ns:xmpp-stanzas' targetNamespace='urn:ietf:params:xml:ns:xmpp-stanzas'
xmlns='urn:ietf:params:xml:ns:xmpp-stanzas' xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'
skipping to change at page 77, line 10 skipping to change at page 77, line 18
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='urn:ietf:params:xml:ns:xmpp-stanzas' targetNamespace='urn:ietf:params:xml:ns:xmpp-stanzas'
xmlns='urn:ietf:params:xml:ns:xmpp-stanzas' xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='condition'> <xs:element name='condition'>
<xs:complexType> <xs:complexType>
<xs:any <xs:choice>
namespace='##other'
minOccurs='0'
maxOccurs='1'/>
<xs:choice maxOccurs='1'>
<xs:element ref='bad-request'/> <xs:element ref='bad-request'/>
<xs:element ref='feature-not-implemented'/> <xs:element ref='feature-not-implemented'/>
<xs:element ref='forbidden'/> <xs:element ref='forbidden'/>
<xs:element ref='internal-server-error'/> <xs:element ref='internal-server-error'/>
<xs:element ref='item-not-found'/>
<xs:element ref='jid-malformed'/> <xs:element ref='jid-malformed'/>
<xs:element ref='jid-not-found'/>
<xs:element ref='not-allowed'/> <xs:element ref='not-allowed'/>
<xs:element ref='recipient-unavailable'/> <xs:element ref='recipient-unavailable'/>
<xs:element ref='registration-required'/> <xs:element ref='registration-required'/>
<xs:element ref='remote-server-not-found'/> <xs:element ref='remote-server-not-found'/>
<xs:element ref='remove-server-timeout'/> <xs:element ref='remove-server-timeout'/>
<xs:element ref='service-unavailable'/> <xs:element ref='service-unavailable'/>
</xs:choice> </xs:choice>
</xs:complexType> </xs:complexType>
<xs:element name='bad-request'/> <xs:element name='bad-request' type='conditionType'/>
<xs:element name='feature-not-implemented'/> <xs:element name='feature-not-implemented' type='conditionType'/>
<xs:element name='forbidden'/> <xs:element name='forbidden' type='conditionType'/>
<xs:element name='internal-server-error'/> <xs:element name='internal-server-error' type='conditionType'/>
<xs:element name='jid-malformed'/> <xs:element name='item-not-found' type='conditionType'/>
<xs:element name='jid-not-found'/> <xs:element name='jid-malformed' type='conditionType'/>
<xs:element name='not-allowed'/> <xs:element name='not-allowed' type='conditionType'/>
<xs:element name='recipient-unavailable'/> <xs:element name='recipient-unavailable' type='conditionType'/>
<xs:element name='registration-required'/> <xs:element name='registration-required' type='conditionType'/>
<xs:element name='remote-server-not-found'/> <xs:element name='remote-server-not-found' type='conditionType'/>
<xs:element name='remote-server-timeout'/> <xs:element name='remote-server-timeout' type='conditionType'/>
<xs:element name='service-unavailable'/> <xs:element name='service-unavailable' type='conditionType'/>
<xs:complexType name='conditionType'>
<xs:any namespace='##other' minOccurs='0' maxOccurs='1'/>
</xs:complexType>
</xs:schema> </xs:schema>
Appendix B. Revision History Appendix B. Revision History
Note to RFC Editor: please remove this entire appendix, and the Note to RFC Editor: please remove this entire appendix, and the
corresponding entries in the table of contents, prior to publication. corresponding entries in the table of contents, prior to publication.
B.1 Changes from draft-ietf-xmpp-core-09 B.1 Changes from draft-ietf-xmpp-core-09
o Adjusted TLS content regarding certificate validation process.
o Specified that stanza error extensions for specific applications
are to be properly namespaced children of the relevant descriptive
element.
o Clarified rules for inclusion of the 'id' attribute.
o Specified that the 'xml:lang' attribute SHOULD be included (per
list discussion).
o Made small editorial changes and fixed several schema errors.
B.2 Changes from draft-ietf-xmpp-core-09
o Fixed several dialback error conditions. o Fixed several dialback error conditions.
o Cleaned up business rules regarding TLS and certificate processing o Cleaned up business rules regarding TLS and certificate processing
based on off-list feedback. based on off-list feedback.
o Changed <stream-condition/> and <stanza-condition/> elements to o Changed <stream-condition/> and <stanza-condition/> elements to
<condition/>. <condition/>.
o Added or modified several stream and stanza error conditions. o Added or modified several stream and stanza error conditions.
o Specified only one child allowed for IQ, or two if type="error". o Specified only one child allowed for IQ, or two if type="error".
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
B.2 Changes from draft-ietf-xmpp-core-08 B.3 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.
B.3 Changes from draft-ietf-xmpp-core-07 B.4 Changes from draft-ietf-xmpp-core-07
o Made several small editorial changes. o Made several small editorial changes.
B.4 Changes from draft-ietf-xmpp-core-06 B.5 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 [25]. to the format defined in The IETF XML Registry [25].
o Removed note to RFC Editor regarding provisional namespace names. o Removed note to RFC Editor regarding provisional namespace names.
B.5 Changes from draft-ietf-xmpp-core-05 B.6 Changes from draft-ietf-xmpp-core-05
o Added <invalid-namespace/> as a stream error condition. o Added <invalid-namespace/> as a stream error condition.
o Adjusted security considerations per discussion at IETF 56 and on o Adjusted security considerations per discussion at IETF 56 and on
list. list.
B.6 Changes from draft-ietf-xmpp-core-04 B.7 Changes from draft-ietf-xmpp-core-04
o Added server-to-server examples for TLS and SASL. o Added server-to-server examples for TLS and SASL.
o Changed error syntax, rules, and examples based on list o Changed error syntax, rules, and examples based on list
discussion. discussion.
o Added schemas for the TLS, stream error, and stanza error o Added schemas for the TLS, stream error, and stanza error
namespaces. namespaces.
o Added note to RFC Editor regarding provisional namespace names. o Added note to RFC Editor regarding provisional namespace names.
o Made numerous small editorial changes and clarified text o Made numerous small editorial changes and clarified text
throughout. throughout.
B.7 Changes from draft-ietf-xmpp-core-03 B.8 Changes from draft-ietf-xmpp-core-03
o Clarified rules and procedures for TLS and SASL. o Clarified rules and procedures for TLS and SASL.
o Amplified stream error code syntax per list discussion. o Amplified stream error code syntax per list discussion.
o Made numerous small editorial changes. o Made numerous small editorial changes.
B.8 Changes from draft-ietf-xmpp-core-02 B.9 Changes from draft-ietf-xmpp-core-02
o Added dialback schema. o Added dialback schema.
o Removed all DTDs since schemas provide more complete definitions. o Removed all DTDs since schemas provide more complete definitions.
o Added stream error codes. o Added stream error codes.
o Clarified error code "philosophy". o Clarified error code "philosophy".
B.9 Changes from draft-ietf-xmpp-core-01 B.10 Changes from draft-ietf-xmpp-core-01
o Updated the addressing restrictions per list discussion and added o Updated the addressing restrictions per list discussion and added
references to the new nodeprep and resourceprep profiles. references to the new nodeprep and resourceprep profiles.
o Corrected error in Stream Authentication regarding "version='1.0'" o Corrected error in Stream Authentication regarding "version='1.0'"
flag. flag.
o Made numerous small editorial changes. o Made numerous small editorial changes.
B.10 Changes from draft-ietf-xmpp-core-00 B.11 Changes from draft-ietf-xmpp-core-00
o Added information about TLS from list discussion. o Added information about TLS from list discussion.
o Clarified meaning of "ignore" based on list discussion. o Clarified meaning of "ignore" based on list discussion.
o Clarified information about Universal Character Set data and o Clarified information about Universal Character Set data and
character encodings. character encodings.
o Provided base64-decoded information for examples. o Provided base64-decoded information for examples.
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
o Made numerous small editorial fixes. o Made numerous small editorial fixes.
B.11 Changes from draft-miller-xmpp-core-02 B.12 Changes from draft-miller-xmpp-core-02
o Brought Streams Authentication section into line with discussion o Brought Streams Authentication section into line with discussion
on list and at IETF 55 meeting. on list and at IETF 55 meeting.
o Added information about the optional 'xml:lang' attribute per o Added information about the optional 'xml:lang' attribute per
discussion on list and at IETF 55 meeting. discussion on list and at IETF 55 meeting.
o Specified that validation is neither required nor recommended, and o Specified that validation is neither required nor recommended, and
that the formal definitions (DTDs and schemas) are included for that the formal definitions (DTDs and schemas) are included for
descriptive purposes only. descriptive purposes only.
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".
o Specified that compliant server implementations must process o Specified that compliant server implementations must process
stanzas in order. stanzas in order.
o Specified that for historical reasons some server implementations o Specified that for historical reasons some server implementations
may accept 'stream:' as the only valid namespace prefix on the may accept 'stream:' as the only valid namespace prefix on the
root stream element. root stream element.
o Clarified the difference between 'jabber:client' and o Clarified the difference between 'jabber:client' and
'jabber:server' namespaces, namely, that 'to' and 'from' 'jabber:server' namespaces, namely, that 'to' and 'from'
 End of changes. 167 change blocks. 
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