draft-ietf-xmpp-core-18.txt   draft-ietf-xmpp-core-19.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft J. Miller Internet-Draft J. Miller
Expires: March 7, 2004 Jabber Software Foundation Expires: April 25, 2004 Jabber Software Foundation
September 7, 2003 October 26, 2003
XMPP Core XMPP Core
draft-ietf-xmpp-core-18 draft-ietf-xmpp-core-19
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract Abstract
This document describes the core features of the Extensible Messaging This memo defines the core features of the Extensible Messaging and
and Presence Protocol (XMPP), a protocol for streaming XML [1] Presence Protocol (XMPP), a protocol for streaming XML [1] elements
elements in order to exchange messages and presence information in in order to exchange messages and presence information in close to
close to real time. While XMPP provides a generalized, extensible real time. While XMPP provides a generalized, extensible framework
framework for transporting structured information, it is used mainly for transporting structured information, it is used mainly for the
for the purpose of building instant messaging and presence purpose of building instant messaging and presence applications that
applications that meet the requirements of RFC 2779. meet the requirements of RFC 2779.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 6
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 6 1.3 Discussion Venue . . . . . . . . . . . . . . . . . . . . . 6
1.4 Intellectual Property Notice . . . . . . . . . . . . . . . . 6 1.4 Intellectual Property Notice . . . . . . . . . . . . . . . 6
2. Generalized Architecture . . . . . . . . . . . . . . . . . . 7 2. Generalized Architecture . . . . . . . . . . . . . . . . . 6
2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Server . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Server . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . 9 3. Addressing Scheme . . . . . . . . . . . . . . . . . . . . 8
3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . . 9 3.2 Domain Identifier . . . . . . . . . . . . . . . . . . . . 9
3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . . 10 3.3 Node Identifier . . . . . . . . . . . . . . . . . . . . . 9
3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . . 10 3.4 Resource Identifier . . . . . . . . . . . . . . . . . . . 9
4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . . 11 3.5 Formal Syntax . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.6 Determination of Addresses . . . . . . . . . . . . . . . . 10
4.2 Stream Attributes . . . . . . . . . . . . . . . . . . . . . 12 4. XML Streams . . . . . . . . . . . . . . . . . . . . . . . 11
4.2.1 Version Support . . . . . . . . . . . . . . . . . . . . . . 13 4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . . 14 4.2 Stream Attributes . . . . . . . . . . . . . . . . . . . . 13
4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . . 14 4.2.1 Version Support . . . . . . . . . . . . . . . . . . . . . 14
4.5 Stream Encryption and Authentication . . . . . . . . . . . . 15 4.3 Namespace Declarations . . . . . . . . . . . . . . . . . . 15
4.6 Stream Errors . . . . . . . . . . . . . . . . . . . . . . . 15 4.4 Stream Features . . . . . . . . . . . . . . . . . . . . . 15
4.6.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.5 Stream Encryption and Authentication . . . . . . . . . . . 15
4.6.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.6 Stream Errors . . . . . . . . . . . . . . . . . . . . . . 15
4.6.3 Defined Conditions . . . . . . . . . . . . . . . . . . . . . 16 4.6.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6.4 Application-Specific Conditions . . . . . . . . . . . . . . 18 4.6.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.7 Simple Streams Example . . . . . . . . . . . . . . . . . . . 19 4.6.3 Defined Conditions . . . . . . . . . . . . . . . . . . . . 17
5. Stream Encryption . . . . . . . . . . . . . . . . . . . . . 21 4.6.4 Application-Specific Conditions . . . . . . . . . . . . . 19
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.7 Simplified Stream Examples . . . . . . . . . . . . . . . . 19
5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 23 5. Stream Encryption . . . . . . . . . . . . . . . . . . . . 21
5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . . 24 5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . . 25 5.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 23
6. Stream Authentication . . . . . . . . . . . . . . . . . . . 28 5.3 Client-to-Server Example . . . . . . . . . . . . . . . . . 24
6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 28 5.4 Server-to-Server Example . . . . . . . . . . . . . . . . . 26
6.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . . 29 6. Stream Authentication . . . . . . . . . . . . . . . . . . 28
6.3 SASL Errors . . . . . . . . . . . . . . . . . . . . . . . . 31 6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.4 SASL Definition . . . . . . . . . . . . . . . . . . . . . . 32 6.2 Narrative . . . . . . . . . . . . . . . . . . . . . . . . 29
6.5 Client-to-Server Example . . . . . . . . . . . . . . . . . . 32 6.3 SASL Definition . . . . . . . . . . . . . . . . . . . . . 31
6.6 Server-to-Server Example . . . . . . . . . . . . . . . . . . 35 6.4 SASL Errors . . . . . . . . . . . . . . . . . . . . . . . 32
7. Server Dialback . . . . . . . . . . . . . . . . . . . . . . 39 6.5 Client-to-Server Example . . . . . . . . . . . . . . . . . 33
7.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 39 6.6 Server-to-Server Example . . . . . . . . . . . . . . . . . 36
7.2 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7. Resource Binding . . . . . . . . . . . . . . . . . . . . . 39
8. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . . 45 8. Server Dialback . . . . . . . . . . . . . . . . . . . . . 41
8.1 Common Attributes . . . . . . . . . . . . . . . . . . . . . 45 8.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.1.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 8.2 Order of Events . . . . . . . . . . . . . . . . . . . . . 42
8.1.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 8.3 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 44
8.1.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 9. XML Stanzas . . . . . . . . . . . . . . . . . . . . . . . 47
8.1.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 9.1 Common Attributes . . . . . . . . . . . . . . . . . . . . 48
8.1.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . . 46 9.1.1 to . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.2 Basic Semantics . . . . . . . . . . . . . . . . . . . . . . 47 9.1.2 from . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.2.1 Message Semantics . . . . . . . . . . . . . . . . . . . . . 47 9.1.3 id . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.2.2 Presence Semantics . . . . . . . . . . . . . . . . . . . . . 47 9.1.4 type . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.2.3 IQ Semantics . . . . . . . . . . . . . . . . . . . . . . . . 47 9.1.5 xml:lang . . . . . . . . . . . . . . . . . . . . . . . . . 50
8.3 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . . 49 9.2 Basic Semantics . . . . . . . . . . . . . . . . . . . . . 50
8.3.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 9.2.1 Message Semantics . . . . . . . . . . . . . . . . . . . . 50
8.3.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 9.2.2 Presence Semantics . . . . . . . . . . . . . . . . . . . . 50
8.3.3 Defined Conditions . . . . . . . . . . . . . . . . . . . . . 51 9.2.3 IQ Semantics . . . . . . . . . . . . . . . . . . . . . . . 51
8.3.4 Application-Specific Conditions . . . . . . . . . . . . . . 52 9.3 Stanza Errors . . . . . . . . . . . . . . . . . . . . . . 52
9. XML Usage within XMPP . . . . . . . . . . . . . . . . . . . 54 9.3.1 Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 52
9.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 54 9.3.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 53
9.2 XML Namespace Names and Prefixes . . . . . . . . . . . . . . 54 9.3.3 Defined Conditions . . . . . . . . . . . . . . . . . . . . 54
9.2.1 Stream Namespace . . . . . . . . . . . . . . . . . . . . . . 54 9.3.4 Application-Specific Conditions . . . . . . . . . . . . . 56
9.2.2 Default Namespace . . . . . . . . . . . . . . . . . . . . . 55 10. XML Usage within XMPP . . . . . . . . . . . . . . . . . . 57
9.2.3 Dialback Namespace . . . . . . . . . . . . . . . . . . . . . 55 10.1 Restrictions . . . . . . . . . . . . . . . . . . . . . . . 57
9.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . . 56 10.2 XML Namespace Names and Prefixes . . . . . . . . . . . . . 57
9.4 Inclusion of Text Declaration . . . . . . . . . . . . . . . 56 10.2.1 Streams Namespace . . . . . . . . . . . . . . . . . . . . 57
9.5 Character Encoding . . . . . . . . . . . . . . . . . . . . . 56 10.2.2 Default Namespace . . . . . . . . . . . . . . . . . . . . 58
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 57 10.2.3 Dialback Namespace . . . . . . . . . . . . . . . . . . . . 58
10.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . . 57 10.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . 59
10.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . . 57 10.4 Inclusion of Text Declaration . . . . . . . . . . . . . . 59
10.3 XML Namespace Name for Stream Errors . . . . . . . . . . . . 57 10.5 Character Encoding . . . . . . . . . . . . . . . . . . . . 59
10.4 XML Namespace Name for Stanza Errors . . . . . . . . . . . . 58 11. IANA Considerations . . . . . . . . . . . . . . . . . . . 59
10.5 Nodeprep Profile of Stringprep . . . . . . . . . . . . . . . 58 11.1 XML Namespace Name for TLS Data . . . . . . . . . . . . . 59
10.6 Resourceprep Profile of Stringprep . . . . . . . . . . . . . 58 11.2 XML Namespace Name for SASL Data . . . . . . . . . . . . . 60
10.7 Existing Registrations . . . . . . . . . . . . . . . . . . . 59 11.3 XML Namespace Name for Stream Errors . . . . . . . . . . . 60
11. Internationalization Considerations . . . . . . . . . . . . 60 11.4 XML Namespace Name for Resource Binding . . . . . . . . . 60
12. Security Considerations . . . . . . . . . . . . . . . . . . 61 11.5 XML Namespace Name for Stanza Errors . . . . . . . . . . . 61
12.1 High Security . . . . . . . . . . . . . . . . . . . . . . . 61 11.6 Nodeprep Profile of Stringprep . . . . . . . . . . . . . . 61
12.2 Client-to-Server Communications . . . . . . . . . . . . . . 61 11.7 Resourceprep Profile of Stringprep . . . . . . . . . . . . 61
12.3 Server-to-Server Communications . . . . . . . . . . . . . . 62 11.8 GSSAPI Service Name . . . . . . . . . . . . . . . . . . . 62
12.4 Order of Layers . . . . . . . . . . . . . . . . . . . . . . 63 11.9 Port Numbers . . . . . . . . . . . . . . . . . . . . . . . 62
12.5 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . 63 12. Internationalization Considerations . . . . . . . . . . . 62
12.6 Mandatory to Implement Technologies . . . . . . . . . . . . 63 13. Security Considerations . . . . . . . . . . . . . . . . . 62
12.7 Stringprep Profiles . . . . . . . . . . . . . . . . . . . . 63 13.1 High Security . . . . . . . . . . . . . . . . . . . . . . 62
13. Server Rules for Handling XML Stanzas . . . . . . . . . . . 65 13.2 Client-to-Server Communications . . . . . . . . . . . . . 63
13.1 No 'to' Address . . . . . . . . . . . . . . . . . . . . . . 65 13.3 Server-to-Server Communications . . . . . . . . . . . . . 64
13.2 Foreign Domain . . . . . . . . . . . . . . . . . . . . . . . 65 13.4 Order of Layers . . . . . . . . . . . . . . . . . . . . . 65
13.3 Subdomain . . . . . . . . . . . . . . . . . . . . . . . . . 66 13.5 Mandatory-to-Implement Technologies . . . . . . . . . . . 65
13.4 Bare Domain or Specific Resource . . . . . . . . . . . . . . 66 13.6 Firewalls . . . . . . . . . . . . . . . . . . . . . . . . 65
13.5 Node in Same Domain . . . . . . . . . . . . . . . . . . . . 66 13.7 Use of base64 in SASL . . . . . . . . . . . . . . . . . . 65
14. Compliance Requirements . . . . . . . . . . . . . . . . . . 68 13.8 Stringprep Profiles . . . . . . . . . . . . . . . . . . . 66
14.1 Servers . . . . . . . . . . . . . . . . . . . . . . . . . . 68 14. Server Rules for Handling XML Stanzas . . . . . . . . . . 67
14.2 Clients . . . . . . . . . . . . . . . . . . . . . . . . . . 68 14.1 No 'to' Address . . . . . . . . . . . . . . . . . . . . . 67
Normative References . . . . . . . . . . . . . . . . . . . . 70 14.2 Foreign Domain . . . . . . . . . . . . . . . . . . . . . . 67
Informative References . . . . . . . . . . . . . . . . . . . 72 14.3 Subdomain . . . . . . . . . . . . . . . . . . . . . . . . 68
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 72 14.4 Mere Domain or Specific Resource . . . . . . . . . . . . . 68
A. Nodeprep . . . . . . . . . . . . . . . . . . . . . . . . . . 73 14.5 Node in Same Domain . . . . . . . . . . . . . . . . . . . 68
A.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 73 15. Compliance Requirements . . . . . . . . . . . . . . . . . 69
A.2 Character Repertoire . . . . . . . . . . . . . . . . . . . . 73 15.1 Servers . . . . . . . . . . . . . . . . . . . . . . . . . 69
A.3 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 73 15.2 Clients . . . . . . . . . . . . . . . . . . . . . . . . . 69
A.4 Normalization . . . . . . . . . . . . . . . . . . . . . . . 73 Normative References . . . . . . . . . . . . . . . . . . . 70
A.5 Prohibited Output . . . . . . . . . . . . . . . . . . . . . 74 Informative References . . . . . . . . . . . . . . . . . . 71
A.6 Bidirectional Characters . . . . . . . . . . . . . . . . . . 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . 72
B. Resourceprep . . . . . . . . . . . . . . . . . . . . . . . . 76 A. Nodeprep . . . . . . . . . . . . . . . . . . . . . . . . . 72
B.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 76 A.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 72
B.2 Character Repertoire . . . . . . . . . . . . . . . . . . . . 76 A.2 Character Repertoire . . . . . . . . . . . . . . . . . . . 73
B.3 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 76 A.3 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 73
B.4 Normalization . . . . . . . . . . . . . . . . . . . . . . . 76 A.4 Normalization . . . . . . . . . . . . . . . . . . . . . . 73
B.5 Prohibited Output . . . . . . . . . . . . . . . . . . . . . 77 A.5 Prohibited Output . . . . . . . . . . . . . . . . . . . . 73
B.6 Bidirectional Characters . . . . . . . . . . . . . . . . . . 77 A.6 Bidirectional Characters . . . . . . . . . . . . . . . . . 74
C. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . . 78 B. Resourceprep . . . . . . . . . . . . . . . . . . . . . . . 74
C.1 Stream namespace . . . . . . . . . . . . . . . . . . . . . . 78 B.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 75
C.2 Stream error namespace . . . . . . . . . . . . . . . . . . . 79 B.2 Character Repertoire . . . . . . . . . . . . . . . . . . . 75
C.3 TLS namespace . . . . . . . . . . . . . . . . . . . . . . . 80 B.3 Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 75
C.4 SASL namespace . . . . . . . . . . . . . . . . . . . . . . . 81 B.4 Normalization . . . . . . . . . . . . . . . . . . . . . . 75
C.5 Dialback namespace . . . . . . . . . . . . . . . . . . . . . 82 B.5 Prohibited Output . . . . . . . . . . . . . . . . . . . . 76
C.6 Stanza error namespace . . . . . . . . . . . . . . . . . . . 83 B.6 Bidirectional Characters . . . . . . . . . . . . . . . . . 76
D. Differences Between Jabber and XMPP . . . . . . . . . . . . 85 C. XML Schemas . . . . . . . . . . . . . . . . . . . . . . . 76
D.1 Authentication . . . . . . . . . . . . . . . . . . . . . . . 85 C.1 Streams namespace . . . . . . . . . . . . . . . . . . . . 76
D.2 Channel Encryption . . . . . . . . . . . . . . . . . . . . . 85 C.2 Stream error namespace . . . . . . . . . . . . . . . . . . 78
D.3 JID Processing . . . . . . . . . . . . . . . . . . . . . . . 85 C.3 TLS namespace . . . . . . . . . . . . . . . . . . . . . . 79
D.4 Error Handling . . . . . . . . . . . . . . . . . . . . . . . 86 C.4 SASL namespace . . . . . . . . . . . . . . . . . . . . . . 79
D.5 Internationalization . . . . . . . . . . . . . . . . . . . . 86 C.5 Resource binding namespace . . . . . . . . . . . . . . . . 81
D.6 Stream Version Attribute . . . . . . . . . . . . . . . . . . 86 C.6 Dialback namespace . . . . . . . . . . . . . . . . . . . . 81
E. Revision History . . . . . . . . . . . . . . . . . . . . . . 87 C.7 Stanza error namespace . . . . . . . . . . . . . . . . . . 82
E.1 Changes from draft-ietf-xmpp-core-17 . . . . . . . . . . . . 87 D. Differences Between Core Jabber Protocol and XMPP . . . . 83
E.2 Changes from draft-ietf-xmpp-core-16 . . . . . . . . . . . . 87 D.1 Channel Encryption . . . . . . . . . . . . . . . . . . . . 84
E.3 Changes from draft-ietf-xmpp-core-15 . . . . . . . . . . . . 88 D.2 Authentication . . . . . . . . . . . . . . . . . . . . . . 84
E.4 Changes from draft-ietf-xmpp-core-14 . . . . . . . . . . . . 88 D.3 Resource Binding . . . . . . . . . . . . . . . . . . . . . 84
E.5 Changes from draft-ietf-xmpp-core-13 . . . . . . . . . . . . 88 D.4 JID Processing . . . . . . . . . . . . . . . . . . . . . . 84
E.6 Changes from draft-ietf-xmpp-core-12 . . . . . . . . . . . . 88 D.5 Error Handling . . . . . . . . . . . . . . . . . . . . . . 85
E.7 Changes from draft-ietf-xmpp-core-11 . . . . . . . . . . . . 89 D.6 Internationalization . . . . . . . . . . . . . . . . . . . 85
E.8 Changes from draft-ietf-xmpp-core-10 . . . . . . . . . . . . 89 D.7 Stream Version Attribute . . . . . . . . . . . . . . . . . 85
E.9 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . . 89 E. Revision History . . . . . . . . . . . . . . . . . . . . . 85
E.10 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . . 89 E.1 Changes from draft-ietf-xmpp-core-18 . . . . . . . . . . . 85
E.11 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . . 90 E.2 Changes from draft-ietf-xmpp-core-17 . . . . . . . . . . . 86
E.12 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . . 90 E.3 Changes from draft-ietf-xmpp-core-16 . . . . . . . . . . . 87
E.13 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . . 90 E.4 Changes from draft-ietf-xmpp-core-15 . . . . . . . . . . . 87
E.14 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . . 90 E.5 Changes from draft-ietf-xmpp-core-14 . . . . . . . . . . . 87
E.15 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . . 91 E.6 Changes from draft-ietf-xmpp-core-13 . . . . . . . . . . . 88
E.16 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . . 91 E.7 Changes from draft-ietf-xmpp-core-12 . . . . . . . . . . . 88
E.17 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . . 91 E.8 Changes from draft-ietf-xmpp-core-11 . . . . . . . . . . . 88
E.18 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . . 91 E.9 Changes from draft-ietf-xmpp-core-10 . . . . . . . . . . . 89
E.19 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . . 92 E.10 Changes from draft-ietf-xmpp-core-09 . . . . . . . . . . . 89
Intellectual Property and Copyright Statements . . . . . . . 94 E.11 Changes from draft-ietf-xmpp-core-08 . . . . . . . . . . . 89
E.12 Changes from draft-ietf-xmpp-core-07 . . . . . . . . . . . 89
E.13 Changes from draft-ietf-xmpp-core-06 . . . . . . . . . . . 90
E.14 Changes from draft-ietf-xmpp-core-05 . . . . . . . . . . . 90
E.15 Changes from draft-ietf-xmpp-core-04 . . . . . . . . . . . 90
E.16 Changes from draft-ietf-xmpp-core-03 . . . . . . . . . . . 90
E.17 Changes from draft-ietf-xmpp-core-02 . . . . . . . . . . . 91
E.18 Changes from draft-ietf-xmpp-core-01 . . . . . . . . . . . 91
E.19 Changes from draft-ietf-xmpp-core-00 . . . . . . . . . . . 91
E.20 Changes from draft-miller-xmpp-core-02 . . . . . . . . . . 91
Intellectual Property and Copyright Statements . . . . . . 93
1. Introduction 1. Introduction
1.1 Overview 1.1 Overview
The Extensible Messaging and Presence Protocol (XMPP) is an open XML The Extensible Messaging and Presence Protocol (XMPP) is an open XML
[1] protocol for near-real-time messaging, presence, and [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
adaptation of the Jabber protocol that would be suitable as an IETF adaptation of the Jabber protocol that would be suitable as an IETF
instant messaging (IM) and presence technology. As a result of work instant messaging (IM) and presence technology. As a result of work
by the XMPP WG, the current document defines the core features of by the XMPP WG, the current memo defines the core features of XMPP;
XMPP; XMPP IM [20] defines the extensions required to provide the XMPP IM [21] defines the extensions required to provide the instant
instant messaging and presence functionality defined in RFC 2779 [2]. messaging and presence functionality defined in RFC 2779 [2].
1.2 Terminology 1.2 Terminology
The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL", The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC "OPTIONAL" in this document are to be interpreted as described in RFC
2119 [3]. 2119 [3].
1.3 Discussion Venue 1.3 Discussion Venue
skipping to change at page 7, line 10 skipping to change at page 6, line 49
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 usually has been implemented via a typical date it usually has been implemented via a typical client-server
client-server architecture, wherein a client utilizing XMPP accesses architecture, wherein a client utilizing XMPP accesses a server over
a server over a TCP [4] socket. a TCP [4] socket.
The following diagram provides a high-level overview of this The following diagram provides a high-level overview of this
architecture (where "-" represents communications that use XMPP and architecture (where "-" represents communications that use XMPP and
"=" represents communications that use any other protocol). "=" represents communications that use any other protocol).
C1 - S1 - S2 - C3 C1 - S1 - S2 - C3
/ \ / \
C2 - G1 = FN1 = FC1 C2 - G1 = FN1 = FC1
The symbols are as follows: The symbols are as follows:
skipping to change at page 7, line 42 skipping to change at page 7, line 33
o FC1 -- A client on a foreign messaging network o FC1 -- A client on a foreign messaging network
2.2 Server 2.2 Server
A server acts as an intelligent abstraction layer for XMPP A server acts as an intelligent abstraction layer for XMPP
communications. Its primary responsibilities are to manage communications. Its primary responsibilities are to manage
connections from or sessions for other entities (in the form of XML connections from or sessions for other entities (in the form of XML
streams (Section 4) to and from authorized clients, servers, and streams (Section 4) to and from authorized clients, servers, and
other entities) and to route appropriately-addressed XML stanzas other entities) and to route appropriately-addressed XML stanzas
(Section 8) among such entities over XML streams. Most XMPP-compliant (Section 9) among such entities over XML streams. Most XMPP-compliant
servers also assume responsibility for the storage of data that is servers also assume responsibility for the storage of data that is
used by clients (e.g., contact lists for users of XMPP-based instant used by clients (e.g., contact lists for users of XMPP-based instant
messaging and presence applications); in this case, the XML data is messaging and presence applications); in this case, the XML data is
processed directly by the server itself on behalf of the client and processed directly by the server itself on behalf of the client and
is not routed to another entity. Compliant server implementations is not routed to another entity. Compliant server implementations
MUST ensure in-order processing of XML stanzas between any two MUST ensure in-order processing of XML stanzas between any two
entities. entities.
2.3 Client 2.3 Client
Most clients connect directly to a server over a TCP socket and use Most clients connect directly to a server over a TCP socket and use
XMPP to take full advantage of the functionality provided by a server XMPP to take full advantage of the functionality provided by a server
and any associated services. Although 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 [21] polling or some other mechanism), this specification HTTP [22] polling or some other mechanism), this specification
defines a binding of XMPP to TCP only. Multiple resources (e.g., defines a binding of XMPP to TCP only. Multiple resources (e.g.,
devices or locations) MAY connect simultaneously to a server on devices or locations) MAY connect simultaneously to a server on
behalf of each authorized client, with each resource connecting over behalf of each authorized client, with each resource differentiated
a discrete TCP socket and differentiated by the resource identifier by the resource identifier of a JID (e.g., <node@domain/home> vs.
of a JID (e.g., <user@domain/home> vs. <user@domain/work>) as defined <node@domain/work>) as defined under Addressing Scheme (Section 3).
under Addressing Scheme (Section 3). The port registered with the The RECOMMENDED port for connections between a client and a server is
Internet Assigned Numbers Authority (IANA) [5] for connections 5222, as registered with the Internet Assigned Numbers Authority
between a client and a server is 5222 (see IANA Considerations (IANA) [5] (see Port Numbers (Section 11.9)).
(Section 10)).
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), SIMPLE, SMTP, and legacy instant
networks such as AIM, ICQ, MSN Messenger, and Yahoo! Instant messaging networks such as AIM, ICQ, MSN Messenger, and Yahoo!
Messenger. Communications between gateways and servers, and between Instant Messenger. Communications between gateways and servers, and
gateways and the foreign messaging system, are not defined in this between gateways and the foreign messaging system, are not defined in
document. this document.
2.5 Network 2.5 Network
Because each server is identified by a network address and because Because each server is identified by a network address and because
server-to-server communications are a straightforward extension of server-to-server communications are a straightforward extension of
the client-to-server protocol, in practice the system consists of a the client-to-server protocol, in practice the system consists of a
network of servers that inter-communicate. Thus user-a@domain1 is network of servers that inter-communicate. Thus user-a@domain1 is
able to exchange messages, presence, and other information with able to exchange messages, presence, and other information with
user-b@domain2. This pattern is familiar from messaging protocols user-b@domain2. This pattern is familiar from messaging protocols
(such as SMTP) that make use of network addressing standards. (such as SMTP) that make use of network addressing standards.
Communications between any two servers are OPTIONAL; if enabled, such Communications between any two servers are OPTIONAL. If enabled, such
communications occur over XML streams that are normally bound to TCP communications SHOULD occur over XML streams that are bound to TCP
sockets, using port 5269 as registered with the IANA (see IANA sockets. The RECOMMENDED port for connections between servers is
Considerations (Section 10)). 5222, as registered with the Internet Assigned Numbers Authority
(IANA) [5] (see Port Numbers (Section 11.9)).
3. Addressing Scheme 3. Addressing Scheme
3.1 Overview 3.1 Overview
An entity is anything that can be considered a network endpoint An entity is anything that can be considered a network endpoint
(i.e., an ID on the network) and that can communicate using XMPP. All (i.e., an ID on the network) and that can communicate using XMPP. 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 [22]. For historical reasons, the address of such an with RFC 2396 [23]. For historical reasons, the address of such an
entity is called a Jabber Identifier or JID. A valid JID contains a entity is called a Jabber Identifier or JID. A valid JID contains a
set of ordered elements formed of a domain identifier, node set of ordered elements formed of a domain identifier, node
identifier, and resource identifier in the following format: identifier, and resource identifier in the following format:
[node@]domain[/resource]. Each allowable portion of a JID (node [node@]domain[/resource]. Each allowable portion of a JID (node
identifier, domain identifier, and resource identifier) may be up to identifier, domain identifier, and resource identifier) may be up to
1023 bytes in length, resulting in a maximum total size (including 1023 bytes in length, resulting in a maximum total size (including
the '@' and '/' separators) of 3071 bytes. the '@' and '/' separators) of 3071 bytes.
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 instant messaging user, the server this structure is to identify an instant messaging user, the server
to which the user connects, and the user's active session or to which the user connects, and the user's active session or
connection (e.g., a specific client) in the form of <user@domain/ connection (e.g., a specific client) in the form of <user@host/
resource>. However, node types other than clients are possible; for resource>. However, node types other than clients are possible; for
example, a specific chat room offered by a multi-user chat service example, a specific chat room offered by a multi-user chat service
could be addressed as <room@service> (where "room" is the name of the could be addressed as <room@service> (where "room" is the name of the
chat room and "service" is the hostname of the multi-user chat chat room and "service" is the hostname of the multi-user chat
service) and a specific occupant of such a room could be addressed as service) and a specific occupant of such a room could be addressed as
<room@service/nick> (where "nick" is the occupant's room nickname). <room@service/nick> (where "nick" is the occupant's room nickname).
Many other JID types are possible (e.g., <domain/resource> could be a Many other JID types are possible (e.g., <domain/resource> could be a
server-side script or service). server-side script or service).
3.2 Domain Identifier 3.2 Domain Identifier
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It usually represents the network gateway or "primary" server to It usually represents the network gateway or "primary" server to
which other entities connect for XML routing and data management which other entities connect for XML routing and data management
capabilities. However, the entity referenced by a domain identifier capabilities. However, the entity referenced by a domain identifier
is not always a server, and may be a service that is addressed as a is not always a server, and may be a service that is addressed as a
subdomain of a server and that provides functionality above and subdomain of a server and that provides functionality above and
beyond the capabilities of a server (e.g., a multi-user chat service, beyond the capabilities of a server (e.g., a multi-user chat service,
a user directory, or a gateway to a foreign messaging system). a user directory, or a gateway to a foreign messaging system).
The domain identifier for every server or service that will The domain identifier for every server or service that will
communicate over a network SHOULD resolve to a Fully Qualified Domain communicate over a network SHOULD resolve to a Fully Qualified Domain
Name. A domain identifier MUST conform to RFC 952 [6] and RFC 1123 Name. A domain identifier MUST be not more than 1023 bytes in length
[7]. In addition, a domain identifier MUST be no more than 1023 bytes and MUST conform to the Nameprep [6] profile of stringprep [7].
in length and MUST conform to the Nameprep [8] profile of stringprep
[9].
3.3 Node Identifier 3.3 Node Identifier
The node identifier is an optional secondary identifier placed before The node identifier is an optional secondary identifier placed before
the domain identifier and separated from the latter by the '@' the domain identifier and separated from the latter by the '@'
character. It usually represents the entity requesting and using character. It usually represents the entity requesting and using
network access provided by the server or gateway (i.e., a client), network access provided by the server or gateway (i.e., a client),
although it can also represent other kinds of entities (e.g., a chat although it can also represent other kinds of entities (e.g., a chat
room associated with a multi-user chat service). The entity room associated with a multi-user chat service). The entity
represented by a node identifier is addressed within the context of a represented by a node identifier is addressed within the context of a
specific domain; within instant messaging and presence applications specific domain; within instant messaging and presence applications
of XMPP this address is called a "bare JID" and is of the form of XMPP this address is called a "bare JID" and is of the form
<node@domain>. <node@domain>.
A node identifier MUST be no more than 1023 bytes in length and MUST A node identifier MUST be no more than 1023 bytes in length and MUST
conform to the Nodeprep (Appendix A) profile of stringprep [9]. conform to the Nodeprep (Appendix A) profile of stringprep [7].
3.4 Resource Identifier 3.4 Resource Identifier
The resource identifier is an optional tertiary identifier placed The resource identifier is an optional tertiary identifier placed
after the domain identifier and separated from the latter by the '/' after the domain identifier and separated from the latter by the '/'
character. A resource identifier may modify either a <user@domain> or character. A resource identifier may modify either a <node@domain> or
mere <domain> address. It usually represents a specific session, mere <domain> address. It usually represents a specific session,
connection (e.g., a device or location), or object (e.g., a connection (e.g., a device or location), or object (e.g., a
participant in a multi-user chat room) belonging to the entity participant in a multi-user chat room) belonging to the entity
associated with a node identifier. A resource identifier is opaque to associated with a node identifier. A resource identifier is opaque to
both servers and other clients, and is typically defined by a client both servers and other clients, and is typically defined by a client
implementation when it provides the information necessary to complete implementation when it provides the information necessary to complete
stream authentication (Section 6). An entity may maintain multiple Resource Binding (Section 7) (although it may be generated by a
server on behalf of a client). An entity may maintain multiple
resources simultaneously. 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 (Appendix B) profile of stringprep MUST conform to the Resourceprep (Appendix B) profile of stringprep
[9]. [7].
3.5 Formal Syntax
The syntax for a JID is defined below using Augmented Backus-Naur
Form as defined in RFC 2234 [8]. The IPv4address and IPv6address
rules are defined in Appendix B of RFC 2373 [9]; the hostname rule is
defined in Section 3.2.2 of RFC 2396 [23]; the allowable character
sequences that conform to the node rule are defined by the Nodeprep
(Appendix A) profile of stringprep [7] as documented in this memo;
the allowable character sequences that conform to the resource rule
are defined by the Resourceprep (Appendix B) profile of stringprep
[7] as documented in this memo.
jid = [ node "@" ] domain [ "/" resource ]
domain = hostname / IPv4address / IPv6address
3.6 Determination of Addresses
After Stream Authentication (Section 6) and, if appropriate, Resource
Binding (Section 7), the receiving entity for a stream MUST determine
the initiating entity's JID.
For server-to-server communications, the initiating entity's JID
SHOULD be the authorization identity, derived from the authentication
identity as defined in RFC 2222 [13] if no authorization identity was
specified during stream authentication.
For client-to-server communications, the "bare JID" (<node@domain>)
SHOULD be the authorization identity, derived from the authentication
identity as defined in RFC 2222 [13] if no authorization identity was
specified during stream authentication; the resource identifier
portion of the "full JID" (<node@domain/resource>) SHOULD be the
resource identifier negotiated by the client and server during
Resource Binding (Section 7).
The receiving entity MUST ensure that the resulting JID (including
node identifier, domain identifier, resource identifier, and
separator characters) conforms to the rules and formats defined
earlier in this section.
4. XML Streams 4. XML Streams
4.1 Overview 4.1 Overview
Two fundamental concepts make possible the rapid, asynchronous Two fundamental concepts make possible the rapid, asynchronous
exchange of relatively small payloads of structured information exchange of relatively small payloads of structured information
between presence-aware entities: XML streams and XML stanzas. These between presence-aware entities: XML streams and XML stanzas. These
terms may be defined as follows: terms are defined as follows:
Definition of XML Stream: An XML stream is a container for the Definition of XML Stream: An XML stream is a container for the
exchange of XML elements between any two entities over a network. exchange of XML elements between any two entities over a network.
An XML stream is negotiated from an initiating entity (usually a An XML stream is negotiated from an initiating entity (usually a
client or server) to a receiving entity (usually a server), client or server) to a receiving entity (usually a server),
normally over a TCP socket, and corresponds to the initiating normally over a TCP socket, and corresponds to the initiating
entity's "session" with the receiving entity. The start of the XML entity's "session" with the receiving entity. The start of the 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), while (with appropriate attributes and namespace declarations), while
the end of the XML stream is denoted unambiguously by a closing the end of the XML stream is denoted unambiguously by a closing
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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 of the XML stream (e.g., <presence>), element start tag at depth=1 of the XML stream (e.g., <presence>),
and the end of any XML stanza is denoted unambiguously by the and the end of any XML stanza is denoted unambiguously by the
corresponding close tag at depth=1 (e.g., </presence>). An XML corresponding close tag at depth=1 (e.g., </presence>). An XML
stanza MAY contain child elements (with accompanying attributes, stanza MAY contain child elements (with accompanying attributes,
elements, and CDATA) as necessary in order to convey the desired elements, and CDATA) as necessary in order to convey the desired
information. An XML element sent for the purpose of stream information. The only defined XML stanzas are <message/>,
encryption, stream authentication, or server dialback is not <presence/>, and <iq/> as defined under XML Stanzas (Section 9);
considered to be an XML stanza. an XML element sent for the purpose of stream encryption (Section
5), stream authentication (Section 6), or server dialback (Section
8) is not considered to be an XML stanza.
Consider the example of a client's session with a server. In order to Consider the example of a client's session with a server. In order 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 and the character encoding
encoding (see also Character Encoding (Section 9.5)). The server supported (see Inclusion of Text Declaration (Section 10.4); see also
SHOULD then reply with a second XML stream back to the client, again Character Encoding (Section 10.5)). Subject to local policies and
optionally preceded by a text declaration. Once the client has service provisioning, the server SHOULD then reply with a second XML
authenticated with the server (see Section 6), the client MAY send an stream back to the client, again optionally preceded by a text
unlimited number of XML stanzas over the stream to any recipient on declaration. Once the client has completed Stream Authentication
the network. When the client desires to close the stream, it simply (Section 6), the client MAY send an unbounded number of XML stanzas
sends a closing </stream> tag to the server (alternatively, the over the stream to any recipient on the network. When the client
stream may be closed by the server), after which both the client and desires to close the stream, it simply sends a closing </stream> tag
server SHOULD close the underlying TCP connection as well. to the server (alternatively, the stream may be closed by the
server), after which both the client and server SHOULD close the
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 in a simplistic
follows: fashion as follows:
|--------------------| |--------------------|
| <stream> | | <stream> |
|--------------------| |--------------------|
| <presence> | | <presence> |
| <show/> | | <show/> |
| </presence> | | </presence> |
|--------------------| |--------------------|
| <message to='foo'> | | <message to='foo'> |
| <body/> | | <body/> |
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o id -- The 'id' attribute SHOULD be used only in the XML stream o id -- The 'id' attribute SHOULD be used only in the XML stream
header from the receiving entity to the initiating entity. This header from the receiving entity to the initiating entity. This
attribute is a unique identifier created by the receiving entity attribute is a unique identifier created by the receiving entity
to function as a session key for the initiating entity's streams to function as a session key for the initiating entity's streams
with the receiving entity, and MUST be unique within the receiving with the receiving entity, and MUST be unique within the receiving
application (normally a server). There SHOULD be no 'id' attribute application (normally a server). There SHOULD be no 'id' attribute
on the XML stream header sent from the initiating entity to the on 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 xml:lang -- An 'xml:lang' attribute (as defined in Section 2.12 of
the XML specification [1]) SHOULD be included by the initiating
entity on the header for the initial stream to specify the default
language of any human-readable XML character data it sends over
that stream. If included, the receiving entity SHOULD remember
that value as the default for both the initial stream and the
response stream; if not included, the receiving entity SHOULD use
a configurable default value for both streams, which it MUST
communicate in the header for the response stream. For all stanzas
sent over the initial stream, if the initiating entity does not
include an 'xml:lang' attribute, the receiving entity SHOULD apply
the default value; if the initiating entity does include an
'xml:lang' attribute, the receiving entity MUST NOT modify or
delete it (see also xml:lang (Section 9.1.5)). The value of the
'xml:lang' attribute MUST be an NMTOKEN and MUST conform to the
format defined in RFC 3066 [16].
o version -- The presence of the version attribute set to a value of o version -- The presence of the version attribute set to a value of
"1.0" signals support for the stream features defined in this "1.0" signals support for the stream-related protocols (including
specification. Detailed rules regarding generation and handling of stream features) defined in this specification. Detailed rules
this attribute are defined below. regarding generation and handling of this attribute are defined
below.
We can summarize as follows: We can summarize 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
xml:lang | default language | default language
version | signals XMPP 1.0 support | signals XMPP 1.0 support version | signals XMPP 1.0 support | signals XMPP 1.0 support
4.2.1 Version Support 4.2.1 Version Support
The following rules apply to the generation and handling of the The following rules apply to the generation and handling of the
'version' attribute: 'version' attribute:
1. If the initiating entity complies with the XML streams protocol 1. If the initiating entity complies with the XML streams protocol
defined herein (including Stream Encryption (Section 5), Stream defined herein (including Stream Encryption (Section 5), Stream
Authentication (Section 6), and Stream Errors (Section 4.6)), it Authentication (Section 6), and Stream Errors (Section 4.6)), it
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and underlying TCP connection. and underlying TCP connection.
5. If the receiving entity includes the 'version' attribute set to a 5. If the receiving entity includes the 'version' attribute set to a
value other than "1.0" in its stream header response, the value other than "1.0" in its stream header response, the
initiating entity SHOULD generate an <unsupported-version/> initiating entity SHOULD generate an <unsupported-version/>
stream error and terminate the XML stream and underlying TCP stream error and terminate the XML stream and underlying TCP
connection. connection.
4.3 Namespace Declarations 4.3 Namespace Declarations
The stream element MUST possess both a stream namespace declaration The stream element MUST possess both a streams namespace declaration
and a default namespace declaration (as "namespace declaration" is and a default namespace declaration (as "namespace declaration" is
defined in the XML namespaces specification [10]). For detailed defined in the XML namespaces specification [10]). For detailed
information regarding the stream namespace and default namespace, see information regarding the streams namespace and default namespace,
Namespace Names and Prefixes (Section 9.2). see Namespace Names and Prefixes (Section 10.2).
4.4 Stream Features 4.4 Stream Features
If the initiating entity includes the 'version' attribute set to a If the initiating entity includes the 'version' attribute set to a
value of "1.0" in its initiating stream element, the receiving entity value of "1.0" in the initial stream header, the receiving entity
MUST send a <features/> child element (prefixed by the stream MUST send a <features/> child element (prefixed by the streams
namespace prefix) to the initiating entity in order to announce any namespace prefix) to the initiating entity in order to announce any
stream-level features that can be negotiated (or capabilities that stream-level features that can be negotiated (or capabilities that
otherwise need to be advertised). Currently this is used for TLS and otherwise need to be advertised). Currently this is used only for
SASL negotiation only, but it could be used for other negotiable Stream Encryption (Section 5), Stream Authentication (Section 6), and
features in the future (usage is defined under Stream Encryption Resource Binding (Section 7) as defined herein, and for Session
(Section 5) and Stream Authentication (Section 6) below). If an Establishment as defined in XMPP IM [21]; however, the stream
entity does not understand or support some features, it SHOULD features functionality could be used to advertise other negotiable
silently ignore them. features in the future. If an entity does not understand or support
some features, it SHOULD silently ignore them.
4.5 Stream Encryption and Authentication 4.5 Stream Encryption and Authentication
XML streams in XMPP 1.0 SHOULD be encrypted as defined under Stream XML streams in XMPP 1.0 SHOULD be encrypted as defined under Stream
Encryption (Section 5) and MUST be authenticated as defined under Encryption (Section 5) and MUST be authenticated as defined under
Stream Authentication (Section 6). If the initiating entity attempts Stream Authentication (Section 6). If the initiating entity attempts
to send an XML stanza before the stream is authenticated, the to send an XML Stanza (Section 9) before the stream has been
receiving entity SHOULD return a <not-authorized/> stream error to authenticated, the receiving entity SHOULD return a <not-authorized/>
the initiating entity and then terminate both the XML stream and the stream error to the initiating entity and then terminate both the XML
underlying TCP connection. stream and the underlying TCP connection.
4.6 Stream Errors 4.6 Stream Errors
The root stream element MAY contain an <error/> child element that is The root stream element MAY contain an <error/> child element that is
prefixed by the stream namespace prefix. The error child MUST be sent prefixed by the streams namespace prefix. The error child MUST be
by a compliant entity (usually a server rather than a client) if it sent by a compliant entity (usually a server rather than a client) if
perceives that a stream-level error has occurred. it perceives that a stream-level error has occurred.
4.6.1 Rules 4.6.1 Rules
The following rules apply to stream-level errors: The following rules apply to stream-level errors:
o It is assumed that all stream-level errors are unrecoverable; o It is assumed that all stream-level errors are unrecoverable;
therefore, if an error occurs at the level of the stream, the therefore, if an error occurs at the level of the stream, the
entity that detects the error MUST send a stream error to the entity that detects the error MUST send a stream error to the
other entity, send a closing </stream> tag, and terminate the other entity, send a closing </stream> tag, and terminate the
underlying TCP connection. underlying TCP connection.
skipping to change at page 16, line 11 skipping to change at page 16, line 43
OPTIONAL descriptive text OPTIONAL descriptive text
</text> </text>
[OPTIONAL application-specific condition element] [OPTIONAL application-specific condition element]
</stream:error> </stream:error>
The <error/> element: The <error/> element:
o MUST contain a child element corresponding to one of the defined o MUST contain a child element corresponding to one of the defined
stanza error conditions defined below; this element MUST be stanza error conditions defined below; this element MUST be
qualified by the 'urn:ietf:params:xml:ns:xmpp-streamstreams' qualified by the 'urn:ietf:params:xml:ns:xmpp-streamstreams'
namespace namespace (this namespace name adheres to the format defined in
The IETF XML Registry [24])
o MAY contain a <text/> child containing CDATA that describes the o MAY contain a <text/> child containing CDATA that describes the
error in more detail; this element MUST be qualified by the error in more detail; this element MUST be qualified by the
'urn:ietf:params:xml:ns:xmpp-streams' namespace and SHOULD possess 'urn:ietf:params:xml:ns:xmpp-streams' namespace and SHOULD possess
an 'xml:lang' attribute an 'xml:lang' attribute
o MAY contain a child element for an application-specific error o MAY contain a child element for an application-specific error
condition; this element MUST be qualified by an condition; this element MUST be qualified by an
application-defined namespace, and its structure is defined by application-defined namespace, and its structure is defined by
that namespace that namespace
The <text/> element is OPTIONAL. If included, it SHOULD be used only The <text/> element is OPTIONAL. If included, it SHOULD be used only
to provide descriptive or diagnostic information that supplements the to provide descriptive or diagnostic information that supplements the
meaning of a defined condition or application-specific condition. It meaning of a defined condition or application-specific condition. It
SHOULD NOT be interpreted programmatically by an application. It SHOULD NOT be interpreted programmatically by an application. It
SHOULD NOT be used as the error message presented to user, but MAY be SHOULD NOT be used as the error message presented to a user, but MAY
shown in addition to the error message associated with the included be shown in addition to the error message associated with the
condition element (or elements). included condition element (or elements).
Note: the XML namespace name 'urn:ietf:params:xml:ns:xmpp-streams'
that qualifies the descriptive element adheres to the format defined
in The IETF XML Registry [23].
4.6.3 Defined Conditions 4.6.3 Defined Conditions
The following stream-level error conditions are defined: The following stream-level error conditions are defined:
o <bad-format/> -- the entity has sent XML that cannot be processed; o <bad-format/> -- the entity has sent XML that cannot be processed;
this error may be used rather than more specific XML-related this error MAY be used rather than more specific XML-related
errors such as <bad-namespace-prefix/>, <invalid-xml/>, errors such as <bad-namespace-prefix/>, <invalid-xml/>,
<restricted-xml/>, <unsupported-encoding/>, and <restricted-xml/>, <unsupported-encoding/>, and
<xml-not-well-formed/>, although the more specific errors are <xml-not-well-formed/>, although the more specific errors are
preferred. preferred.
o <bad-namespace-prefix/> -- the entity has sent a namespace prefix o <bad-namespace-prefix/> -- the entity has sent a namespace prefix
that is unsupported, or has sent no namespace prefix on an element that is unsupported, or has sent no namespace prefix on an element
that requires such a prefix (see the XML Namespace Names and that requires such a prefix (see XML Namespace Names and Prefixes
Prefixes (Section 9.2) section of this document). (Section 10.2)).
o <conflict/> -- the server is closing the active stream for this o <conflict/> -- the server is closing the active stream for this
entity because a new stream has been initiated that conflicts with entity because a new stream has been initiated that conflicts with
the existing stream. the existing stream.
o <connection-timeout/> -- the entity has not generated any traffic o <connection-timeout/> -- the entity has not generated any traffic
over the stream for some period of time (configurable according to over the stream for some period of time (configurable according to
a local service policy). a local service policy).
o <host-gone/> -- the value of the 'to' attribute provided by the o <host-gone/> -- the value of the 'to' attribute provided by the
skipping to change at page 17, line 26 skipping to change at page 18, line 9
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. hostname that is hosted by the server.
o <improper-addressing/> -- a stanza sent between two servers lacks o <improper-addressing/> -- a stanza sent between two servers lacks
a 'to' or 'from' attribute (or the attribute has no value). a 'to' or 'from' attribute (or the attribute has no value).
o <internal-server-error/> -- the server has experienced a o <internal-server-error/> -- the server has experienced a
misconfiguration or an otherwise-undefined internal error that misconfiguration or an otherwise-undefined internal error that
prevents it from servicing the stream. prevents it from servicing the stream.
o <invalid-from/> -- the JID or hostname provided in a 'from'
address does not match an authorized JID or validated domain
negotiated between servers via SASL or dialback, or between a
client and a server via authentication and resource authorization.
o <invalid-id/> -- the stream ID or dialback ID is invalid or does o <invalid-id/> -- the stream ID or dialback ID is invalid or does
not match an ID previously provided. not match an ID previously provided.
o <invalid-namespace/> -- the stream namespace name is something o <invalid-namespace/> -- the streams namespace name is something
other than "http://etherx.jabber.org/streams" or the dialback other than "http://etherx.jabber.org/streams" or the dialback
namespace name is something other than "jabber:server:dialback" namespace name is something other than "jabber:server:dialback"
(see the XML Namespace Names and Prefixes (Section 9.2) section of (see XML Namespace Names and Prefixes (Section 10.2)).
this document).
o <invalid-xml/> -- the entity has sent invalid XML over the stream o <invalid-xml/> -- the entity has sent invalid XML over the stream
to a server that performs validation (see the Validation (Section to a server that performs validation (see Validation (Section
9.3) section of this document). 10.3)).
o <nonmatching-hosts/> -- the hostname provided in a 'from' address
does not match the hostname (or other validated domain) negotiated
via SASL or dialback.
o <not-authorized/> -- the entity has attempted to send data before o <not-authorized/> -- the entity has attempted to send data before
authenticating, or otherwise is not authorized to perform an the stream has been authenticated, or otherwise is not authorized
action related to stream negotiation; the receiving entity SHOULD to perform an action related to stream negotiation; the receiving
silently drop the offending stanza and MUST NOT process it before entity MUST NOT process the offending stanza before sending the
sending the stream error. stream error.
o <policy-violation/> -- the entity has violated some local service o <policy-violation/> -- the entity has violated some local service
policy; the server MAY choose to specify the policy in the <text/> policy; the server MAY choose to specify the policy in the <text/>
element. element.
o <remote-connection-failed/> -- the server is unable to properly o <remote-connection-failed/> -- the server is unable to properly
connect to a remote resource that is required for authentication connect to a remote resource that is required for authentication
or authorization. or authorization.
o <resource-constraint/> -- the server is resource-constrained and o <resource-constraint/> -- the server lacks the system resources
is unable to service the stream. necessary to service the stream.
o <restricted-xml/> -- the entity has attempted to send a comment, o <restricted-xml/> -- the entity has attempted to send restricted
processing instruction, DTD, entity reference, or unescaped XML features such as a comment, processing instruction, DTD,
character (see the Restrictions (Section 9.1) section of this entity reference, or unescaped character (see Restrictions
document). (Section 10.1)).
o <see-other-host/> -- the server will not provide service to the o <see-other-host/> -- the server will not provide service to the
initiating entity but is redirecting traffic to another host; the initiating entity but is redirecting traffic to another host; the
server SHOULD specify the alternate hostname or IP address in the server SHOULD specify the alternate hostname or IP address in the
<text/> element. CDATA of the <see-other-host/> element.
o <system-shutdown/> -- the server is being shut down and all active o <system-shutdown/> -- the server is being shut down and all active
streams are being closed. streams are being closed.
o <undefined-condition/> -- the error condition is not one of those o <undefined-condition/> -- the error condition is not one of those
defined by the other conditions in this list; this error condition defined by the other conditions in this list; this error condition
SHOULD be used only in conjunction with an application-specific SHOULD be used only in conjunction with an application-specific
condition. condition.
o <unsupported-encoding/> -- the initiating entity has encoded the o <unsupported-encoding/> -- the initiating entity has encoded the
stream in an encoding that is not supported by the server (see the stream in an encoding that is not supported by the server (see
Character Encoding (Section 9.5) section of this document). Character Encoding (Section 10.5)).
o <unsupported-stanza-type/> -- the initiating entity has sent a o <unsupported-stanza-type/> -- the initiating entity has sent a
first-level child of the stream that is not supported by the first-level child of the stream that is not supported by the
server. server.
o <unsupported-version/> -- the value of the 'version' attribute o <unsupported-version/> -- the value of the 'version' attribute
provided by the initiating entity in the stream header specifies a provided by the initiating entity in the stream header specifies a
version of XMPP that is not supported by the server; the server version of XMPP that is not supported by the server; the server
MAY specify the version(s) it supports in the <text/> element. MAY specify the version(s) it supports in the <text/> element.
skipping to change at page 19, line 16 skipping to change at page 19, line 47
<stream:error> <stream:error>
<xml-not-well-formed <xml-not-well-formed
xmlns='urn:ietf:params:xml:ns:xmpp-streams'/> xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>
<text xml:lang='en' xmlns='urn:ietf:params:xml:ns:xmpp-streams'> <text xml:lang='en' xmlns='urn:ietf:params:xml:ns:xmpp-streams'>
Some special application diagnostic information! Some special application diagnostic information!
</text> </text>
<escape-your-data xmlns='application-ns'/> <escape-your-data xmlns='application-ns'/>
</stream:error> </stream:error>
</stream:stream> </stream:stream>
4.7 Simple Streams Example 4.7 Simplified Stream Examples
The following is a stream-based session of a client on a server This section contains two simplified examples of a stream-based
(where the "C" lines are sent from the client to the server, and the "session" of a client on a server (where the "C" lines are sent from
"S" lines are sent from the server to the client): the client to the server, and the "S" lines are sent from the server
to the client); these examples are included for the purpose of
illustrating the concepts introduced thus far.
A basic session: A basic "session":
C: <?xml version='1.0'?> C: <?xml version='1.0'?>
<stream:stream <stream:stream
to='example.com' to='example.com'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
S: <?xml version='1.0'?> S: <?xml version='1.0'?>
<stream:stream <stream:stream
from='example.com' from='example.com'
id='id_123456789' id='someid'
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 ... ... encryption, authentication, and resource binding ...
C: <message from='juliet@example.com' C: <message from='juliet@example.com'
to='romeo@example.net' to='romeo@example.net'
xml:lang='en'> xml:lang='en'>
C: <body>Art thou not Romeo, and a Montague?</body> C: <body>Art thou not Romeo, and a Montague?</body>
C: </message> C: </message>
S: <message from='romeo@example.net' S: <message from='romeo@example.net'
to='juliet@example.com' to='juliet@example.com'
xml:lang='en'> xml:lang='en'>
S: <body>Neither, fair saint, if either thee dislike.</body> S: <body>Neither, fair saint, if either thee dislike.</body>
S: </message> S: </message>
C: </stream:stream> C: </stream:stream>
S: </stream:stream> S: </stream:stream>
A stream gone bad:
A "session" gone bad:
C: <?xml version='1.0'?> C: <?xml version='1.0'?>
<stream:stream <stream:stream
to='example.com' to='example.com'
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
version='1.0'> version='1.0'>
S: <?xml version='1.0'?> S: <?xml version='1.0'?>
<stream:stream <stream:stream
from='example.com' from='example.com'
id='id_123456789' id='someid'
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 ... ... encryption, authentication, and resource binding ...
C: <message xml:lang='en'> C: <message xml:lang='en'>
<body>Bad XML, no closing body tag! <body>Bad XML, no closing body tag!
</message> </message>
S: <stream:error> S: <stream:error>
<xml-not-well-formed <xml-not-well-formed
xmlns='urn:ietf:params:xml:ns:xmpp-streams'/> xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>
</stream:error> </stream:error>
S: </stream:stream> S: </stream:stream>
5. Stream Encryption 5. 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) [11] protocol, along with a "STARTTLS" Transport Layer Security (TLS) [11] protocol, along with a "STARTTLS"
extension that is modelled after similar extensions for the IMAP extension that is modelled after similar extensions for the IMAP
[24], POP3 [25], and ACAP [26] protocols as described in RFC 2595 [25], POP3 [26], and ACAP [27] protocols as described in RFC 2595
[27]. The namespace name for the STARTTLS extension is [28]. The namespace name for the STARTTLS extension is
'urn:ietf:params:xml:ns:xmpp-tls', which adheres to the format 'urn:ietf:params:xml:ns:xmpp-tls', which adheres to the format
defined in The IETF XML Registry [23]. defined in The IETF XML Registry [24].
An administrator of a given domain MAY require the use of TLS for An administrator of a given domain MAY require the use of TLS for
client-to-server communications, server-to-server communications, or client-to-server communications, server-to-server communications, or
both. Servers SHOULD use TLS between two domains for the purpose of both. Clients SHOULD use TLS to secure the streams prior to
securing server-to-server communications. See Mandatory to Implement attempting to complete Stream Authentication (Section 6), and servers
Technologies (Section 12.6) regarding mechanisms that MUST be SHOULD use TLS between two domains for the purpose of securing
supported. server-to-server communications.
The following rules apply: The following rules apply:
1. An initiating entity that complies with this specification MUST 1. An initiating entity that complies with this specification MUST
include the 'version' attribute set to a value of "1.0" in the include the 'version' attribute set to a value of "1.0" in the
initiating stream header. initial stream header.
2. If the TLS negotiation occurs between two servers, 2. If the TLS negotiation occurs between two servers,
communications MUST NOT proceed until the DNS hostnames asserted communications MUST NOT proceed until the Domain Name System
by the servers have been resolved (see Server-to-Server (DNS) hostnames asserted by the servers have been resolved (see
Communications (Section 12.3)). Server-to-Server Communications (Section 13.3)).
3. When a receiving entity that complies with this specification 3. When a receiving entity that complies with this specification
receives an initiating stream header that includes the 'version' receives an initial stream header that includes the 'version'
attribute set to a value of "1.0", after sending a stream header attribute set to a value of "1.0", after sending a stream header
in reply (including the version flag) it MUST include a in reply (including the version flag) it MUST include a
<starttls/> element (qualified by the <starttls/> element (qualified by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace) along with the list 'urn:ietf:params:xml:ns:xmpp-tls' namespace) along with the list
of other stream features it supports. of other stream features it supports.
4. If the initiating entity chooses to use TLS for stream 4. If the initiating entity chooses to use TLS for stream
encryption, TLS negotiation MUST be completed before proceeding encryption, TLS negotiation MUST be completed before proceeding
to SASL negotiation. to SASL negotiation; this order of negotiation is required in
order to help safeguard authentication information sent during
SASL negotiation, as well as to make it possible to base the use
of the SASL EXTERNAL mechanism on a certificate provided during
prior TLS negotiation.
5. The receiving entity MUST consider the TLS negotiation to have 5. During TLS negotiation, an entity MUST NOT send any white space
begun immediately after sending the closing ">" of the <proceed/ characters (matching production [3] content of the XML
> element. The initiating entity MUST consider the TLS specification [1]) within the root stream element as separators
between elements (any white space characters shown in the TLS
examples below are included for the sake of readability only);
this prohibition helps to ensure proper security layer byte
precision.
6. The receiving entity MUST consider the TLS negotiation to have
begun immediately after sending the closing ">" character of the
<proceed/> element. The initiating entity MUST consider the TLS
negotiation to have begun immediately after receiving the negotiation to have begun immediately after receiving the
closing ">" of the <proceed/> element from the receiving entity. closing ">" character of the <proceed/> element from the
receiving entity.
6. The initiating entity MUST validate the certificate presented by 7. The initiating entity MUST validate the certificate presented by
the receiving entity; there are two cases: the receiving entity; there are two cases:
Case 1 -- The initiating entity has been configured with a set Case 1 -- The initiating entity has been configured with a set
of trusted root certificates: Normal certificate validation of trusted root certificates: Normal certificate validation
processing is appropriate, and SHOULD follow the rules processing is appropriate, and SHOULD follow the rules
defined for HTTP over TLS [12]. The trusted roots may be defined for HTTP over TLS [12]. The trusted roots may be
either a well-known public set or a manually configured Root either a well-known public set or a manually configured Root
CA (e.g., an organization's own Certificate Authority or a CA (e.g., an organization's own Certificate Authority or a
self-signed Root CA for the service as described under High self-signed Root CA for the service as defined under High
Security (Section 12.1)). This case is RECOMMENDED. Security (Section 13.1)). This case is RECOMMENDED.
Case 2 -- The initiating entity has been configured with the Case 2 -- The initiating entity has been configured with the
receiving entity's self-signed service certificate: Simple receiving entity's self-signed service certificate: Simple
comparison of public keys is appropriate. This case is NOT comparison of public keys is appropriate. This case is NOT
RECOMMENDED (see High Security (Section 12.1) for details). RECOMMENDED (see High Security (Section 13.1) for details).
If the above methods fail, the certificate SHOULD be presented If the above methods fail, the certificate SHOULD be presented
to a human (e.g., an end user or server administrator) for to a human (e.g., an end user or server administrator) for
approval; if presented, the receiver MUST deliver the entire approval; if presented, the receiver MUST deliver the entire
certificate chain to the human, who SHOULD be given the option certificate chain to the human, who SHOULD be given the option
to store the Root CA certificate (not the service or End Entity to store the Root CA certificate (not the service or End Entity
certificate) and to not be queried again regarding acceptance of certificate) and to not be queried again regarding acceptance of
the certificate for some reasonable period of time. the certificate for some reasonable period of time.
7. If the TLS negotiation is successful, the receiving entity MUST 8. If the TLS negotiation is successful, the receiving entity MUST
discard any knowledge obtained from the initiating entity before discard any knowledge obtained from the initiating entity before
TLS takes effect. TLS takes effect.
8. If the TLS negotiation is successful, the initiating entity MUST 9. If the TLS negotiation is successful, the initiating entity MUST
discard any knowledge obtained from the receiving entity before discard any knowledge obtained from the receiving entity before
TLS takes effect. TLS takes effect.
9. If the TLS negotiation is successful, the receiving entity MUST 10. If the TLS negotiation is successful, the receiving entity MUST
NOT offer the STARTTLS extension to the initiating entity along NOT offer the STARTTLS extension to the initiating entity along
with the other stream features that are offered when the stream with the other stream features that are offered when the stream
is restarted. is restarted.
10. If the TLS negotiation is successful, the initiating entity 11. If the TLS negotiation is successful, the initiating entity MUST
SHOULD continue with SASL negotiation. continue with SASL negotiation.
11. If the TLS negotiation results in failure, the receiving entity 12. If the TLS negotiation results in failure, the receiving entity
MUST terminate both the XML stream and the underlying TCP MUST terminate both the XML stream and the underlying TCP
connection. connection.
13. See Mandatory-to-Implement Technologies (Section 13.5) regarding
mechanisms that MUST be supported.
5.2 Narrative 5.2 Narrative
When an initiating entity secures a stream with a receiving entity, When an initiating entity secures a stream with a receiving entity,
the steps involved are as follows: the steps involved are as follows:
1. The initiating entity opens a TCP connection and initiates the 1. The initiating entity opens a TCP connection and initiates the
stream by sending the opening XML stream header to the receiving stream by sending the opening XML stream header to the receiving
entity, including the 'version' attribute set to a value of entity, including the 'version' attribute set to a value of
"1.0". "1.0".
skipping to change at page 23, line 37 skipping to change at page 24, line 14
<starttls/> element qualified by the <starttls/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace) to instruct the 'urn:ietf:params:xml:ns:xmpp-tls' namespace) 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 qualified by the or a <failure/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-tls' namespace. If the failure case 'urn:ietf:params:xml:ns:xmpp-tls' namespace. If the failure case
occurs, the receiving entity MUST terminate both the XML stream occurs, the receiving entity MUST terminate both the XML stream
and the underlying TCP connection. If the proceed case occurs, and the underlying TCP connection. If the proceed case occurs,
the receiving entity MUST ignore any further XML data sent over the entities MUST attempt to complete the TLS negotiation over
the XML stream but keep the underlying TCP connection open for the TCP connection and MUST NOT send any further XML data until
the purpose of completing the TLS negotiation. the TLS negotiation is complete.
6. The initiating entity and receiving entity attempt to complete a 6. The initiating entity and receiving entity attempt to complete a
TLS negotiation in accordance with RFC 2246 [11]. TLS negotiation in accordance with RFC 2246 [11].
7. If the TLS negotiation is unsuccessful, the receiving entity MUST 7. If the TLS negotiation is unsuccessful, the receiving entity MUST
terminate the TCP connection. If the TLS negotiation is terminate the TCP connection (it is not necessary to send a
successful, the initiating entity MUST initiate a new stream by closing </stream> tag first, since the receiving entity and
sending an opening XML stream header to the receiving entity. initiating entity MUST consider the original stream to be closed
upon sending or receiving the <success/> element). If the TLS
negotiation is successful, the initiating entity MUST initiate a
new stream by sending an opening XML stream header to the
receiving entity.
8. Upon receiving the new stream header from the initiating entity, 8. Upon receiving the new stream header from the initiating entity,
the receiving entity MUST respond by sending a new XML stream the receiving entity MUST respond by sending a new XML stream
header to the initiating entity along with the remaining header to the initiating entity along with the available features
available features (but NOT including the STARTTLS feature). (but NOT including the STARTTLS feature).
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-registered port 5222 SHOULD be used; stream using STARTTLS (note: the alternate steps shown below are
see IANA Considerations (Section 10)). provided to illustrate the protocol for failure cases; they are not
exhaustive and would not necessarily be triggered by the data sent in
the example).
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='example.com'
version='1.0'> version='1.0'>
Step 2: Server responds by sending a stream tag to client: Step 2: Server responds by sending a stream tag to client:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='c2s_123'
from='capulet.com' from='example.com'
version='1.0'> version='1.0'>
Step 3: Server sends the STARTTLS extension to client along with Step 3: Server sends the STARTTLS extension to client along with
authentication mechanisms and any other stream features: authentication mechanisms and any other stream features:
<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'>
skipping to change at page 25, line 15 skipping to change at page 25, line 49
Step 6: Client and server attempt to complete TLS negotiation over Step 6: Client and server attempt to complete TLS negotiation over
the existing TCP connection. the existing TCP connection.
Step 7: If TLS negotiation is successful, client initiates a new Step 7: If TLS negotiation is successful, client initiates a new
stream to server: 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='example.com'
version='1.0'> version='1.0'>
Step 7 (alt): If TLS negotiation is unsuccessful, Server2 closes TCP
Step 7 (alt): If TLS negotiation is unsuccessful, server MUST close connection.
TCP connection.
Step 8: Server responds by sending a stream header to client along Step 8: Server responds by sending a stream header to client along
with any remaining negotiable stream features: with any available 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'
from='capulet.com' from='example.com'
id='12345678' id='c2s_234'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
<mechanism>EXTERNAL</mechanism> <mechanism>EXTERNAL</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 9: Client SHOULD continue with Stream Authentication (Section Step 9: Client continues with Stream Authentication (Section 6).
6).
5.4 Server-to-Server Example 5.4 Server-to-Server Example
The following example shows the data flow for two servers securing a The following example shows the data flow for two servers securing a
stream using STARTTLS (the IANA-registered port 5269 SHOULD be used; stream using STARTTLS (note: the alternate steps shown below are
see IANA Considerations (Section 10)). provided to illustrate the protocol for failure cases; they are not
exhaustive and would not necessarily be triggered by the data sent in
the example).
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'
to='montague.net' to='example.com'
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'
from='montague.net' from='example.com'
id='12345678' id='s2s_123'
version='1.0'> version='1.0'>
Step 3: Server2 sends the STARTTLS extension to Server1 along with Step 3: Server2 sends the STARTTLS extension to Server1 along with
authentication mechanisms and any other stream features: authentication mechanisms and any other stream features:
<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>
skipping to change at page 27, line 4 skipping to change at page 27, line 40
Step 6: Server1 and Server2 attempt to complete TLS negotiation via Step 6: Server1 and Server2 attempt to complete TLS negotiation via
TCP. TCP.
Step 7: If TLS negotiation is successful, Server1 initiates a new Step 7: If TLS negotiation is successful, Server1 initiates a new
stream to Server2: 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'
to='montague.net' to='example.com'
version='1.0'> version='1.0'>
Step 7 (alt): If TLS negotiation is unsuccessful, server MUST close Step 7 (alt): If TLS negotiation is unsuccessful, server closes TCP
TCP connection. 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 negotiable stream features: with any available 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'
from='montague.net' from='example.com'
id='12345678' id='s2s_234'
version='1.0'> version='1.0'>
<stream:features> <stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>KERBEROS_V4</mechanism> <mechanism>KERBEROS_V4</mechanism>
<mechanism>EXTERNAL</mechanism> <mechanism>EXTERNAL</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 9: Server1 SHOULD continue with Stream Authentication (Section Step 9: Server1 continues with Stream Authentication (Section 6).
6).
6. Stream Authentication 6. Stream Authentication
6.1 Overview 6.1 Overview
XMPP includes a method for authenticating a stream using an XMPP XMPP includes a method for authenticating a stream by means of an
adaptation of the Simple Authentication and Security Layer (SASL) XMPP-specific profile of the Simple Authentication and Security Layer
[13]. SASL provides a generalized method for adding authentication (SASL) [13]. SASL provides a generalized method for adding
support to connection-based protocols, and XMPP uses a generic XML authentication support to connection-based protocols, and XMPP uses a
namespace profile for SASL that conforms to section 4 ("Profiling generic XML namespace profile for SASL that conforms to Section 4
Requirements") of RFC 2222 [13] (the XMPP-specific namespace name is ("Profiling Requirements") of RFC 2222 [13] (the namespace name that
qualifies XML elements used in stream authentication is
'urn:ietf:params:xml:ns:xmpp-sasl', which adheres to the format 'urn:ietf:params:xml:ns:xmpp-sasl', which adheres to the format
defined in The IETF XML Registry [23]). Finally, see Mandatory to defined in The IETF XML Registry [24]).
Implement Technologies (Section 12.6) regarding mechanisms that MUST
be supported.
The following rules apply: The following rules apply:
1. If the SASL negotiation occurs between two servers, 1. If the SASL negotiation occurs between two servers,
communications MUST NOT proceed until the DNS hostnames asserted communications MUST NOT proceed until the Domain Name System
by the servers have been resolved (see Server-to-Server (DNS) hostnames asserted by the servers have been resolved (see
Communications (Section 12.3)). Server-to-Server Communications (Section 13.3)).
2. If TLS is used for stream encryption, SASL SHOULD NOT be used for
anything except stream authentication (i.e., a security layer
SHOULD NOT be negotiated using SASL). Conversely, if a security
layer is to be negotiated via SASL, TLS SHOULD NOT be used.
3. If the initiating entity is capable of authenticating via SASL, 2. If the initiating entity is capable of stream authentication via
it MUST include the 'version' attribute set to a value of "1.0" SASL, it MUST include the 'version' attribute set to a value of
in the initiating stream header. "1.0" in the initial stream header.
4. If the receiving entity is capable of negotiating authentication 3. If the receiving entity is capable of stream authentication via
via SASL, it MUST send one or more authentication mechanisms SASL, it MUST send one or more authentication mechanisms within
within a <mechanisms/> element qualified by the a <mechanisms/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace in response to the 'urn:ietf:params:xml:ns:xmpp-sasl' namespace in reply to the
opening stream tag received from the initiating entity (if the opening stream tag received from the initiating entity (if the
opening stream tag included the 'version' attribute set to a opening stream tag included the 'version' attribute set to a
value of "1.0"). value of "1.0").
5. Upon successful SASL negotiation that involves negotiation of a 4. During SASL negotiation, an entity MUST NOT send any white space
characters (matching production [3] content of the XML
specification [1]) within the root stream element as separators
between elements (any white space characters shown in the SASL
examples below are included for the sake of readability only);
this prohibition helps to ensure proper security layer byte
precision.
5. Any character data contained within the XML elements used during
SASL negotiation MUST be encoded using base64 [14].
6. If supported by the selected SASL mechanism, the initiating
entity SHOULD provide a username during SASL negotiation. The
username-value SHOULD be the initiating entity's sending domain
in the case of server-to-server communications, and SHOULD be
the initiating entity's registered username in the case of
client-to-server communications.
7. If supported by the selected SASL mechanism, the initiating
entity MAY provide an authorization identity during SASL
negotiation, which SHOULD be a non-default identity for which
the entity is seeking authorization to impersonate (i.e., not
the default authorization identity, which is derived from the
authentication identity as described in RFC 2222 [13]). If
provided, the authzid-value MUST be of the form <domain> (i.e.,
a domain identifier only) for servers and of the form
<node@domain> (i.e., node identifier and domain identifier) for
clients.
8. Upon successful SASL negotiation that involves negotiation of a
security layer, the receiving entity MUST discard any knowledge security layer, the receiving entity MUST discard any knowledge
obtained from the initiating entity which was not obtained from obtained from the initiating entity which was not obtained from
the SASL negotiation itself. the SASL negotiation itself.
6. Upon successful SASL negotiation that involves negotiation of a 9. Upon successful SASL negotiation that involves negotiation of a
security layer, the initiating entity MUST discard any knowledge security layer, the initiating entity MUST discard any knowledge
obtained from the receiving entity which was not obtained from obtained from the receiving entity which was not obtained from
the SASL negotiation itself. the SASL negotiation itself.
7. The initiating entity MUST provide an authzid during SASL 10. See Mandatory-to-Implement Technologies (Section 13.5) regarding
negotiation. The authzid-value MUST be a valid JID of the form mechanisms that MUST be supported.
<domain> (i.e., a domain identifier only) for servers and of the
form <user@domain/resource> (i.e., node identifier, domain
identifier, and resource identifier) for clients. The initiating
entity MAY process the authzid-value in accordance with the rules
defined in Addressing Scheme (Section 3) before providing it to
the receiving entity, but is NOT REQUIRED to do so; however, the
receiving entity MUST verify that the authzid-value provided by
the initiating entity conforms to the rules defined therein.
8. Any character data contained within the XML elements used during
SASL negotiation MUST be encoded using base64.
6.2 Narrative 6.2 Narrative
When an initiating entity authenticates with a receiving entity, the When an initiating entity authenticates with a receiving entity, the
steps involved are as follows: steps involved are as follows:
1. The initiating entity requests SASL authentication by including 1. The initiating entity requests SASL authentication by including
the 'version' attribute in the opening XML stream header sent to the 'version' attribute in the opening XML stream header sent to
the receiving entity, with the value set to "1.0". the receiving entity, with the value set to "1.0".
2. After sending an XML stream header in response, the receiving 2. After sending an XML stream header in reply, the receiving entity
entity sends a list of available SASL authentication mechanisms; sends a list of available SASL authentication mechanisms; each of
each of these is a <mechanism/> element included as a child these is a <mechanism/> element included as a child within a
within a <mechanisms/> container element qualified by the <mechanisms/> container element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace, which in turn is a 'urn:ietf:params:xml:ns:xmpp-sasl' namespace, which in turn is a
child of a <features/> element in the streams namespace. If child of a <features/> element in the streams namespace. If
channel encryption needs to be established before a particular Stream Encryption (Section 5) needs to be established before a
authentication mechanism may be used, the receiving entity MUST particular authentication mechanism may be used, the receiving
NOT provide that mechanism in the list of available SASL entity MUST NOT provide that mechanism in the list of available
authentication methods prior to channel encryption. If the SASL authentication mechanisms prior to stream encryption. If the
initiating entity presents a valid certificate during prior TLS initiating entity presents a valid certificate during prior TLS
negotiation, the receiving entity MAY offer the SASL EXTERNAL negotiation, the receiving entity SHOULD offer the SASL EXTERNAL
mechanism to the initiating entity during stream authentication mechanism to the initiating entity during stream authentication
(refer to RFC 2222 [13]). (refer to RFC 2222 [13]), although the EXTERNAL mechanism MAY be
offered under other circumstances as well.
3. The initiating entity selects a mechanism by sending an <auth/> 3. The initiating entity selects a mechanism by sending an <auth/>
element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl' element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl'
namespace to the receiving entity and including an appropriate namespace to the receiving entity and including an appropriate
value for the 'mechanism' attribute; this element MAY optionally value for the 'mechanism' attribute; this element MAY 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 and presented a certificate during prior TLS
from the certificate presented during prior TLS negotiation. negotiation, the authentication credentials SHOULD be taken from
that certificate.
4. If necessary, the receiving entity challenges the initiating 4. If necessary, the receiving entity challenges the initiating
entity by sending a <challenge/> element qualified by the entity by sending a <challenge/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (which entity; this element MAY optionally contain character data (which
MUST be computed in accordance with the SASL mechanism chosen by MUST be computed in accordance with the definition of the SASL
the initiating entity). mechanism chosen by the initiating entity).
5. The initiating entity responds to the challenge by sending a 5. The initiating entity responds to the challenge by sending a
<response/> element qualified by the <response/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the receiving 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the receiving
entity; this element MAY optionally contain character data (which entity; this element MAY optionally contain character data (which
MUST be computed in accordance with the SASL mechanism chosen by MUST be computed in accordance with the definition of the SASL
the initiating entity). mechanism chosen by the initiating entity).
6. If necessary, the receiving entity sends more challenges and the 6. If necessary, the receiving entity sends more challenges and the
initiating entity sends more responses. initiating entity sends more responses.
This series of challenge/response pairs continues until one of three This series of challenge/response pairs continues until one of three
things happens: things happens:
1. The initiating entity aborts the handshake by sending an <abort/> 1. The initiating entity aborts the handshake by sending an <abort/>
element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl' element qualified by the 'urn:ietf:params:xml:ns:xmpp-sasl'
namespace to the receiving entity. Upon receiving the <abort/> namespace to the receiving entity. Upon receiving an <abort/>
element, the receiving entity MUST terminate the TCP connection. element, the receiving entity SHOULD allow a configurable but
reasonable number of retries (at least 2), after which it MUST
terminate the TCP connection; this allows the initiating entity
(e.g., an end-user client) to tolerate incorrectly-provided
credentials (e.g., a mistyped password) without being forced to
reconnect.
2. The receiving entity reports failure of the handshake by sending 2. The receiving entity reports failure of the handshake by sending
a <failure/> element qualified by the a <failure/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity (the particular cause of failure SHOULD be communicated in entity (the particular cause of failure SHOULD be communicated in
an appropriate child element of the <failure/> element as defined an appropriate child element of the <failure/> element as defined
under SASL Errors (Section 6.3)). Immediately after sending the under SASL Errors (Section 6.4)). If the failure case occurs, the
<failure/> element, the receiving entity MUST terminate both the receiving entity SHOULD allow a configurable but reasonable
XML stream and the underlying TCP connection. number of retries (at least 2), after which it MUST terminate the
TCP connection; this allows the initiating entity (e.g., an
end-user client) to tolerate incorrectly-provided credentials
(e.g., a mistyped password) without being forced to reconnect.
3. The receiving entity reports success of the handshake by sending 3. The receiving entity reports success of the handshake by sending
a <success/> element qualified by the a <success/> element qualified by the
'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating 'urn:ietf:params:xml:ns:xmpp-sasl' namespace to the initiating
entity; this element MAY optionally contain character data (in entity; this element MAY optionally contain character data (in
SASL terminology "additional data with success"). Upon receiving SASL terminology, "additional data with success") if required by
the <success/> element, the initiating entity MUST initiate a new the chosen SASL mechanism. Upon receiving the <success/> element,
stream by sending an opening XML stream header to the receiving the initiating entity MUST initiate a new stream by sending an
entity (it is not necessary to send a closing </stream:stream> opening XML stream header to the receiving entity (it is not
element first, since the receiving entity and initiating entity necessary to send a closing </stream> tag first, since the
MUST consider the original stream to be closed upon sending or receiving entity and initiating entity MUST consider the original
receiving the <success/> element). Upon receiving the new stream stream to be closed upon sending or receiving the <success/>
header from the initiating entity, the receiving entity MUST element). Upon receiving the new stream header from the
respond by sending a new XML stream header to the initiating initiating entity, the receiving entity MUST respond by sending a
entity, along with any remaining available features (but NOT new XML stream header to the initiating entity, along with any
including the STARTTLS feature or any authentication mechanisms) available features (but NOT including the STARTTLS feature) or an
or an empty features element (to signify that no additional empty <features/> element (to signify that no additional features
features are available); note that any such additional features are available); any such additional features not defined herein
are not defined herein, and MUST be defined by the relevant MUST be defined by the relevant extension to XMPP.
extension to XMPP.
6.3 SASL Errors
The following SASL-related error conditions are defined:
o <aborted/> -- The receiving entity acknowledges an <abort/>
element sent by the initiating entity; sent in response to the
<abort/> element.
o <bad-protocol/> -- The data provided by the initiating entity
could not be processed, e.g. because does not adhere to the
protocol for the requested mechanism; sent in response to the
<response/> element.
o <encryption-required/> -- The mechanism chosen by the initiating
entity may be used only if the stream is already encrypted; sent
in response to the <auth/> element.
o <invalid-authzid/> -- The authzid provided by the initiating
entity is invalid, either because it is incorrectly formatted or
because the initiating entity does not have permissions to
authorize that ID; sent in response to a <response/> element.
o <invalid-mechanism/> -- The initiating entity did not provide a
mechanism or requested a mechanism that is not supported by the
receiving entity; sent in response to the <auth/> element.
o <invalid-realm/> -- The realm provided by the initiating entity
(in mechanisms that support the concept of a realm) does not match
one of the hostnames served by the receiving entity; sent in
response to a <response/> element.
o <mechanism-too-weak/> -- The mechanism requested by the initiating
entity is weaker than server policy permits for that initiating
entity; sent in response to the <response/> element.
o <not-authorized/> -- The authentication failed because the
initiating entity did not provide valid credentials (this includes
the case of an unknown username); sent in response to a <response/
> element.
o <temporary-auth-failure/> -- The authentication failed because of
a temporary error condition within the receiving entity; sent in
response to an <auth/> element or <response/> element.
6.4 SASL Definition 6.3 SASL Definition
Section 4 of the SASL specification [13] requires that the following Section 4 of the SASL specification [13] requires that the following
information be supplied by a protocol definition: information be supplied by a protocol definition:
service name: "xmpp" service name: "xmpp"
initiation sequence: After the initiating entity provides an opening initiation sequence: After the initiating entity provides an opening
XML stream header and the receiving entity replies in kind, the XML stream header and the receiving entity replies in kind, the
receiving entity provides a list of acceptable authentication receiving entity provides a list of acceptable authentication
methods. The initiating entity chooses one method from the list methods. The initiating entity chooses one method from the list
and sends it to the receiving entity as the value of the and sends it to the receiving entity as the value of the
'mechanism' attribute possessed by an <auth/> element, optionally 'mechanism' attribute possessed by an <auth/> element, optionally
including an initial response to avoid a round trip. including an initial response to avoid a round trip.
exchange sequence: Challenges and responses are carried through the exchange sequence: Challenges and responses are carried through the
exchange of <challenge/> elements from receiving entity to exchange of <challenge/> elements from receiving entity to
initiating entity and <response/> elements from initiating entity initiating entity and <response/> elements from initiating entity
to receiving entity. The receiving entity reports failure by to receiving entity. The receiving entity reports failure by
sending a <failure/> element and success by sending a <success/> sending a <failure/> element and success by sending a <success/>
element; the initiating entity aborts the exchange by sending an element; the initiating entity aborts the exchange by sending an
<abort/> element. (All of these elements are qualified by the <abort/> element. Upon successful negotiation, both sides consider
'urn:ietf:params:xml:ns:xmpp-sasl' namespace.) Upon successful the original XML stream to be closed and new stream headers are
negotiation, both sides consider the original XML stream closed sent by both entities.
and new <stream> headers are sent by both entities.
security layer negotiation: The security layer takes effect security layer negotiation: The security layer takes effect
immediately after sending the closing ">" character of the immediately after sending the closing ">" character of the
<success/> element for the server, and immediately after receiving <success/> element for the receiving entity, and immediately after
the closing ">" character of the <success/> element for the client receiving the closing ">" character of the <success/> element for
(this element is qualified by the the initiating entity. The order of layers is first TCP, then TLS,
'urn:ietf:params:xml:ns:xmpp-sasl' namespace). then SASL, then XMPP.
use of the authorization identity: The authorization identity is used use of the authorization identity: The authorization identity may be
by xmpp to denote the "full JID" (<user@domain/resource>) of a used by xmpp to denote the <node@domain> of a client or the
client or the sending domain of a server. sending <domain> of a server.
6.4 SASL Errors
The following SASL-related error conditions are defined:
o <aborted/> -- The receiving entity acknowledges an <abort/>
element sent by the initiating entity; sent in reply to the
<abort/> element.
o <incorrect-encoding/> -- The data provided by the initiating
entity could not be processed because the base64 [14] encoding is
incorrect; sent in reply to a <response/> element or an <auth/>
element with initial challenge data.
o <invalid-authzid/> -- The authzid provided by the initiating
entity is invalid, either because it is incorrectly formatted or
because the initiating entity does not have permissions to
authorize that ID; sent in reply to a <response/> element or an
<auth/> element with initial challenge data.
o <invalid-mechanism/> -- The initiating entity did not provide a
mechanism or requested a mechanism that is not supported by the
receiving entity; sent in reply to an <auth/> element.
o <mechanism-too-weak/> -- The mechanism requested by the initiating
entity is weaker than server policy permits for that initiating
entity; sent in reply to a <response/> element or an <auth/>
element with initial challenge data.
o <not-authorized/> -- The authentication failed because the
initiating entity did not provide valid credentials (this includes
but is not limited to the case of an unknown username); sent in
reply to a <response/> element or an <auth/> element with initial
challenge data.
o <temporary-auth-failure/> -- The authentication failed because of
a temporary error condition within the receiving entity; sent in
reply to an <auth/> element or <response/> element.
6.5 Client-to-Server Example 6.5 Client-to-Server Example
The following example shows the data flow for a client authenticating The following example shows the data flow for a client authenticating
with a server using SASL (the IANA-registered port 5222 SHOULD be with a server using SASL, normally after successful TLS negotiation
used; see IANA Considerations (Section 10)). (note: the alternate steps shown below are provided to illustrate the
protocol for failure cases; they are not exhaustive and would not
necessarily be triggered by the data sent in the example).
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='example.com'
version='1.0'> version='1.0'>
Step 2: Server responds with a stream tag sent to client: Step 2: Server responds with a stream tag sent to client:
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='c2s_234'
from='capulet.com' from='example.com'
version='1.0'> version='1.0'>
Step 3: Server informs client of available authentication mechanisms: Step 3: Server informs client of available authentication mechanisms:
<stream:features> <stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 4: Client selects an authentication mechanism: Step 4: Client selects an authentication mechanism:
skipping to change at page 33, line 33 skipping to change at page 34, line 15
<stream:features> <stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>DIGEST-MD5</mechanism> <mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism> <mechanism>PLAIN</mechanism>
</mechanisms> </mechanisms>
</stream:features> </stream:features>
Step 4: Client selects an authentication mechanism: Step 4: Client selects an authentication mechanism:
<auth <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='DIGEST-MD5'/> mechanism='DIGEST-MD5'/>
Step 5: Server sends a base64-encoded challenge to client: Step 5: Server sends a base64 [14]-encoded challenge to client:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi cmVhbG09InNvbWVyZWFsbSIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIixxb3A9ImF1dGgi
xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz LGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNzCg==
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ realm="somerealm",nonce="OA6MG9tEQGm2hh",\
qop="auth",charset=utf-8,algorithm=md5-sess qop="auth",charset=utf-8,algorithm=md5-sess
Step 5 (alt): Server returns error to client: Step 5 (alt): Server returns error to client:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism-too-weak/> <incorrect-encoding/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 6: Client responds to the challenge: Step 6: Client sends a base64 [14]-encoded response to the challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
dXNlcm5hbWU9InJvYiIscmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik dXNlcm5hbWU9InNvbWVub2RlIixyZWFsbT0ic29tZXJlYWxtIixub25jZT0i
9BNk1HOXRFUUdtMmhoIixjbm9uY2U9Ik9BNk1IWGg2VnFUclJrIixuYz0w T0E2TUc5dEVRR20yaGgiLGNub25jZT0iT0E2TUhYaDZWcVRyUmsiLG5jPTAw
MDAwMDAwMSxxb3A9YXV0aCxkaWdlc3QtdXJpPSJ4bXBwL2NhdGFjbHlzbS MDAwMDAxLHFvcD1hdXRoLGRpZ2VzdC11cmk9InhtcHAvZXhhbXBsZS5jb20i
5jeCIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNh LHJlc3BvbnNlPWQzODhkYWQ5MGQ0YmJkNzYwYTE1MjMyMWYyMTQzYWY3LGNo
ZjcsY2hhcnNldD11dGYtOCxhdXRoemlkPSJyb2JAY2F0YWNseXNtLmN4L2 YXJzZXQ9dXRmLTgK
15UmVzb3VyY2Ui
</response> </response>
The decoded response is: The decoded response is:
username="rob",realm="cataclysm.cx",\ username="somenode",realm="somerealm",\
nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\ nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\
nc=00000001,qop=auth,digest-uri="xmpp/cataclysm.cx",\ nc=00000001,qop=auth,digest-uri="xmpp/example.com",\
response=d388dad90d4bbd760a152321f2143af7,charset=utf-8,\ response=d388dad90d4bbd760a152321f2143af7,charset=utf-8
authzid="rob@cataclysm.cx/myResource"
Step 7: Server sends another challenge to client: Step 7: Server sends another base64 [14]-encoded challenge to client:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA== cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZAo=
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
rspauth=ea40f60335c427b5527b84dbabcdfffd rspauth=ea40f60335c427b5527b84dbabcdfffd
Step 7 (alt): Server returns error to client: Step 7 (alt): Server returns error to client:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<invalid-realm/> <mechanism-too-weak/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 8: Client responds to the challenge: Step 8: Client responds to the challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9: Server informs client of successful authentication: Step 9: Server informs client of successful authentication:
<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/> <success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
skipping to change at page 35, line 16 skipping to change at page 35, line 43
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<temporary-auth-failure/> <temporary-auth-failure/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 10: Client initiates a new stream to server: Step 10: Client initiates a new 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='example.com'
version='1.0'> version='1.0'>
Step 11: Server responds by sending a stream header to client along Step 11: Server responds by sending a stream header to client along
with any additional features (or an empty features element): with any additional features (or an empty features element):
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
id='12345678' id='c2s_345'
from='capulet.com' from='example.com'
version='1.0'> version='1.0'>
<stream:features/> <stream:features>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<session xmlns='urn:ietf:params:xml:ns:xmpp-session'>
</stream:features>
6.6 Server-to-Server Example 6.6 Server-to-Server Example
The following example shows the data flow for a server authenticating The following example shows the data flow for a server authenticating
with another server using SASL (the IANA-registered port 5269 SHOULD with another server using SASL, normally after successful TLS
be used; see IANA Considerations (Section 10)). negotiation (note: the alternate steps shown below are provided to
illustrate the protocol for failure cases; they are not exhaustive
and would not necessarily be triggered by the data sent in the
example).
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'
to='montague.net' to='example.com'
version='1.0'> version='1.0'>
Step 2: Server2 responds with a stream tag sent to Server1: Step 2: Server2 responds with a stream tag sent to Server1:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
from='montague.net' from='example.com'
id='12345678' id='s2s_234'
version='1.0'> version='1.0'>
Step 3: Server2 informs Server1 of available authentication Step 3: Server2 informs Server1 of available authentication
mechanisms: mechanisms:
<stream:features> <stream:features>
<mechanisms xmlns='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>
Step 4: Server1 selects an authentication mechanism: Step 4: Server1 selects an authentication mechanism:
<auth <auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
xmlns='urn:ietf:params:xml:ns:xmpp-sasl'
mechanism='DIGEST-MD5'/> mechanism='DIGEST-MD5'/>
Step 5: Server2 sends a base64-encoded challenge to Server1: Step 5: Server2 sends a base64 [14]-encoded challenge to Server1:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi dXNlcm5hbWU9InNvbWVkb21haW4iLHJlYWxtPSJzb21lcmVhbG0iLG5vbmNl
xxb3A9ImF1dGgiLGNoYXJzZXQ9dXRmLTgsYWxnb3JpdGhtPW1kNS1zZXNz PSJPQTZNRzl0RVFHbTJoaCIscW9wPSJhdXRoIixjaGFyc2V0PXV0Zi04LGFs
Z29yaXRobT1tZDUtc2Vzcwo=
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",\ username="somedomain",realm="somerealm",\
qop="auth",charset=utf-8,algorithm=md5-sess nonce="OA6MG9tEQGm2hh",qop="auth",\
charset=utf-8,algorithm=md5-sess
Step 5 (alt): Server2 returns error to Server1: Step 5 (alt): Server2 returns error to Server1:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<encryption-required/> <incorrect-encoding/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 6: Server1 responds to the challenge: Step 6: Server1 sends a base64 [14]-encoded response to the
challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cmVhbG09ImNhdGFjbHlzbS5jeCIsbm9uY2U9Ik9BNk1HOXRFUUdtMmhoIi dXNlcm5hbWU9InNvbWVkb21haW4iLHJlYWxtPSJzb21lcmVhbG0iLG5vbmNl
xjbm9uY2U9Ik9BNk1IWGg2VnFUclJrIixuYz0wMDAwMDAwMSxxb3A9YXV0 PSJPQTZNRzl0RVFHbTJoaCIsY25vbmNlPSJPQTZNSFhoNlZxVHJSayIsbmM9
aCxkaWdlc3QtdXJpPSJ4bXBwL2NhdGFjbHlzbS5jeCIscmVzcG9uc2U9ZD MDAwMDAwMDEscW9wPWF1dGgsZGlnZXN0LXVyaT0ieG1wcC9leGFtcGxlLmNv
M4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcsY2hhcnNldD11dGYt bSIscmVzcG9uc2U9ZDM4OGRhZDkwZDRiYmQ3NjBhMTUyMzIxZjIxNDNhZjcs
OAo= Y2hhcnNldD11dGYtOAo=
</response> </response>
The decoded response is: The decoded response is:
realm="cataclysm.cx",nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\ username="somedomain",realm="somerealm",\
nc=00000001,qop=auth,digest-uri="xmpp/cataclysm.cx",\ nonce="OA6MG9tEQGm2hh",cnonce="OA6MHXh6VqTrRk",\
nc=00000001,qop=auth,digest-uri="xmpp/example.com",\
response=d388dad90d4bbd760a152321f2143af7,charset=utf-8 response=d388dad90d4bbd760a152321f2143af7,charset=utf-8
Step 7: Server2 sends another challenge to Server1: Step 7: Server2 sends another base64 [14]-encoded challenge to
Server1:
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZA== cnNwYXV0aD1lYTQwZjYwMzM1YzQyN2I1NTI3Yjg0ZGJhYmNkZmZmZAo=
</challenge> </challenge>
The decoded challenge is: The decoded challenge is:
rspauth=ea40f60335c427b5527b84dbabcdfffd rspauth=ea40f60335c427b5527b84dbabcdfffd
Step 5 (alt): Server2 returns error to Server1: Step 7 (alt): Server2 returns error to Server1:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<invalid-authzid/> <invalid-authzid/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 8: Server1 responds to the challenge: Step 8: Server1 responds to the challenge:
<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/> <response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 8 (alt): Server1 aborts negotiation:
<abort xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9: Server2 informs Server1 of successful authentication: Step 9: Server2 informs Server1 of successful authentication:
<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/> <success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>
Step 9 (alt): Server2 informs Server1 of failed authentication: Step 9 (alt): Server2 informs Server1 of failed authentication:
<failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'> <failure xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<temporary-auth-failure/> <aborted/>
</failure> </failure>
</stream:stream> </stream:stream>
Step 10: Server1 initiates a new stream to Server2: Step 10: Server1 initiates a new stream to Server2:
<stream:stream <stream:stream
xmlns='jabber:server' xmlns='jabber:server'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
to='montague.net' to='example.com'
version='1.0'> version='1.0'>
Step 11: Server2 responds by sending a stream header to Server1 along Step 11: Server2 responds by sending a stream header to Server1 along
with any additional features (or an empty features element): with any additional features (or an empty features element):
<stream:stream <stream:stream
xmlns='jabber:client' xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
from='montague.net' from='example.com'
id='12345678' id='s2s_345'
version='1.0'> version='1.0'>
<stream:features/> <stream:features/>
7. Server Dialback 7. Resource Binding
7.1 Overview After Stream Authentication (Section 6) with the receiving entity,
the initiating entity MAY want or need to bind a specific resource to
that stream. In general this applies only to clients: in order to
conform to the addressing format (Section 3) and stanza delivery
rules (Section 14) specified herein, there MUST be a resource
identifier associated with the <node@domain> of the client (which is
either generated by the server or provided by the client
application); this ensures that the address for use over that stream
is a "full JID" of the form <node@domain/resource>.
Upon receiving a success indication within the SASL negotiation, the
client MUST send a new stream header to the server, to which the
server MUST respond with a stream header as well as a list of
available stream features. Specifically, if the server requires the
client to bind a resource to the stream after successful stream
authentication, it MUST include an empty <bind/> element qualified by
the 'urn:ietf:params:xml:ns:xmpp-bind' namespace in the stream
features list it presents to the client upon sending the header for
the response stream sent after successful stream authentication (but
not before):
Server advertises resource binding feature to client:
<stream:stream
xmlns='jabber:client'
xmlns:stream='http://etherx.jabber.org/streams'
id='c2s_345'
from='example.com'
version='1.0'>
<stream:features>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
</stream:features>
Upon being so informed that resource binding is required, the client
MUST bind a resource to the stream by sending to the server an IQ
stanza of type "set" (see IQ Semantics (Section 9.2.3)) containing
data qualified by the 'urn:ietf:params:xml:ns:xmpp-bind' namespace.
If the client wishes to allow the server to generate the resource
identifier on its behalf, it sends an IQ stanza of type "set" that
contains an empty <bind/> element:
Client asks server to bind a resource:
<iq type='set' id='bind_1'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/>
</iq>
A server that supports resource binding MUST be able to generate a
resource identifier on behalf of a client. A resource identifier
generated by the server MUST be unique for that <node@domain>.
If the client wishes to specify the resource identifier, it sends an
IQ stanza of type "set" that contains the desired resource identifier
as the CDATA of a <resource/> element that is a child of the <bind/>
element:
Client binds a resource:
<iq type='set' id='bind_2'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<resource>someresource</resource>
</bind>
</iq>
Once the server has generated a resource identifier for the client or
accepted the resource identifier provided by the client, it MUST
return an IQ stanza of type "result" to the client, which MUST
include a <jid/> child element that specifies the full JID for the
client as determined by the server:
Server informs client of successful resource binding:
<iq type='result' id='bind_2'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<jid>somenode@somedomain/someresource</jid>
</bind>
</iq>
A server is NOT REQUIRED to accept the resource identifier provided
by the client, and MAY override it with a resource identifier that
the server generates; in this case, the server SHOULD NOT return a
stanza error (e.g., <forbidden/>) to the client but instead SHOULD
communicate the generated resource identifier to the client in the IQ
result as shown above.
When a client supplies a resource identifier, the following stanza
error conditions may occur (see Stanza Errors (Section 9.3)):
o The provided resource identifier cannot be processed by the server
in accordance with Resourceprep (Appendix B).
o The client is not allowed to bind a resource to the stream (e.g.,
because the client has reached a limit on the number of bound
resources allowed).
o The provided resource identifier is already in use.
The protocol for these error conditions is shown below.
Resource identifier cannot be processed:
<iq type='error' id='bind_2'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<resource>someresource</resource>
</bind>
<error type='modify'>
<bad-request xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error>
</iq>
Client is not allowed to bind a resource:
<iq type='error' id='bind_2'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<resource>someresource</resource>
</bind>
<error type='cancel'>
<not-allowed xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error>
</iq>
Resource identifier is in use:
<iq type='error' id='bind_2'>
<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'>
<resource>someresource</resource>
</bind>
<error type='cancel'>
<conflict xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
</error>
</iq>
8. Server Dialback
8.1 Overview
The Jabber protocol from which XMPP was adapted includes a "server The Jabber protocol from which XMPP was adapted includes a "server
dialback" method for protecting against domain spoofing, thus making dialback" method for protecting against domain spoofing, thus making
it more difficult to spoof XML stanzas (see Server-to-Server it more difficult to spoof XML stanzas (see Server-to-Server
Communications (Section 12.3) regarding this method's security Communications (Section 13.3) regarding this method's security
characteristics). Server dialback also makes it easier to deploy characteristics). Server dialback also makes it easier to deploy
systems in which outbound messages and inbound messages are handled systems in which outbound messages and inbound messages are handled
by different machines for the same domain. The server dialback method by different machines for the same domain. The server dialback method
is made possible by the existence of DNS, since one server can is made possible by the existence of the Domain Name System (DNS),
(normally) discover the authoritative server for a given domain. since one server can (normally) discover the authoritative server for
a given domain.
Because dialback depends on the Domain Name System, inter-domain Because dialback depends on DNS, inter-domain communications MUST NOT
communications MUST NOT proceed until the DNS hostnames asserted by proceed until the DNS hostnames asserted by the servers have been
the servers have been resolved (see Server-to-Server Communications resolved (see Server-to-Server Communications (Section 13.3)).
(Section 12.3)).
The method for generating and verifying the keys used in server The method for generating and verifying the keys used in server
dialback MUST take into account the hostnames being used, the random dialback MUST take into account the hostnames being used, the random
ID generated for the stream, and a secret known by the authoritative ID generated for the stream, and a secret known by the authoritative
server's network. server's network.
Any error that occurs during dialback negotiation MUST be considered Any error that occurs during dialback negotiation MUST be considered
a stream error, resulting in termination of the stream and of the a stream error, resulting in termination of the stream and of the
underlying TCP connection. The possible error conditions are underlying TCP connection. The possible error conditions are
specified in the protocol description below. specified in the protocol description below.
skipping to change at page 39, line 47 skipping to change at page 42, line 38
connection between two domains. connection between two domains.
o Receiving Server -- the server that is trying to authenticate that o Receiving Server -- the server that is trying to authenticate that
Originating Server represents the domain which it claims to be. Originating Server represents the domain which it claims to be.
o Authoritative Server -- the server that answers to the DNS o Authoritative Server -- the server that answers to the DNS
hostname asserted by Originating Server; for basic environments hostname asserted by Originating Server; for basic environments
this will be Originating Server, but it could be a separate this will be Originating Server, but it could be a separate
machine in Originating Server's network. machine in Originating Server's network.
8.2 Order of Events
The following is a brief summary of the order of events in dialback: The following is a brief summary of the order of events in dialback:
1. Originating Server establishes a connection to Receiving Server. 1. Originating Server establishes a connection to Receiving Server.
2. Originating Server sends a 'key' value over the connection to 2. Originating Server sends a 'key' value over the connection to
Receiving Server. Receiving Server.
3. Receiving Server establishes a connection to Authoritative 3. Receiving Server establishes a connection to Authoritative
Server. Server.
skipping to change at page 41, line 7 skipping to change at page 44, line 5
| send dialback key | | send dialback key |
| ----------------------> | | ----------------------> |
| | | |
| validate dialback key | | validate dialback key |
| <---------------------- | | <---------------------- |
| |
| report dialback result | | report dialback result |
| <---------------------- | | <---------------------- |
| | | |
7.2 Protocol 8.3 Protocol
The interaction between the servers is as follows: The detailed protocol interaction between the servers is as follows:
1. Originating Server establishes TCP connection to Receiving 1. Originating Server establishes TCP connection to Receiving
Server. Server.
2. Originating Server sends a stream header to Receiving Server: 2. Originating Server sends a stream header to Receiving Server:
<stream:stream <stream:stream
xmlns:stream='http://etherx.jabber.org/streams' xmlns:stream='http://etherx.jabber.org/streams'
xmlns='jabber:server' xmlns='jabber:server'
xmlns:db='jabber:server:dialback'> xmlns:db='jabber:server:dialback'>
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Server in Step 4. Based on this information as well as shared Server in Step 4. Based on this information as well as shared
secret information within the Authoritative Server's network, secret information within the Authoritative Server's network,
the key is verified. Any verifiable method MAY be used to the key is verified. Any verifiable method MAY be used to
generate the key. If the value of the 'to' address does not generate the key. If the value of the 'to' address does not
match a hostname recognized by Authoritative Server, then match a hostname recognized by Authoritative Server, then
Authoritative Server MUST generate a <host-unknown/> stream Authoritative Server MUST generate a <host-unknown/> stream
error condition and terminate both the XML stream and the error condition and terminate both the XML stream and the
underlying TCP connection. If the value of the 'from' address underlying TCP connection. If the value of the 'from' address
does not match the hostname represented by Receiving Server when does not match the hostname represented by Receiving Server when
opening the TCP connection (or any validated domain), then opening the TCP connection (or any validated domain), then
Authoritative Server MUST generate a <nonmatching-hosts/> stream Authoritative Server MUST generate an <invalid-from/> stream
error condition and terminate both the XML stream and the error condition and terminate both the XML stream and the
underlying TCP connection. underlying TCP connection.
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'
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Note: if the ID does not match that provided by Receiving Server Note: if the ID does not match that provided by Receiving Server
in Step 3, then Receiving Server MUST generate an <invalid-id/> in Step 3, then Receiving Server MUST generate an <invalid-id/>
stream error condition and terminate both the XML stream and the stream error condition and terminate both the XML stream and the
underlying TCP connection. If the value of the 'to' address does underlying TCP connection. If the value of the 'to' address does
not match a hostname recognized by Receiving Server, then not match a hostname recognized by Receiving Server, then
Receiving Server MUST generate a <host-unknown/> stream error Receiving Server MUST generate a <host-unknown/> stream error
condition and terminate both the XML stream and the underlying condition and terminate both the XML stream and the underlying
TCP connection. If the value of the 'from' address does not TCP connection. If the value of the 'from' address does not
match the hostname represented by Originating Server when match the hostname represented by Originating Server when
opening the TCP connection (or any validated domain), then opening the TCP connection (or any validated domain), then
Receiving Server MUST generate a <nonmatching-hosts/> stream Receiving Server MUST generate an <invalid-from/> stream error
error condition and terminate both the XML stream and the condition and terminate both the XML stream and the underlying
underlying TCP connection. TCP connection.
10. Receiving Server informs Originating Server of the result: 10. Receiving Server informs Originating Server of the result:
<db:result <db:result
from='Receiving Server' from='Receiving Server'
to='Originating Server' to='Originating Server'
type='valid'/> type='valid'/>
Note: At this point the connection has either been validated via Note: At this point the connection has either been validated via
a type='valid', or reported as invalid. If the connection is a type='valid', or reported as invalid. If the connection is
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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
<improper-addressing/> stream error condition and terminate both the <improper-addressing/> stream error condition and terminate both the
XML stream and the underlying TCP connection. Furthermore, a server XML stream and the underlying TCP connection. Furthermore, a server
MUST verify that the 'from' attribute of stanzas received from the MUST verify that the 'from' attribute of stanzas received from the
other server includes a validated domain for the stream; if a stanza other server includes a validated domain for the stream; if a stanza
does not meet this restriction, the server that receives the stanza does not meet this restriction, the server that receives the stanza
MUST generate a <nonmatching-hosts/> stream error condition and MUST generate an <invalid-from/> stream error condition and terminate
terminate both the XML stream and the underlying TCP connection. Both both the XML stream and the underlying TCP connection. Both of these
of these checks help to prevent spoofing related to particular checks help to prevent spoofing related to particular stanzas.
stanzas.
8. XML Stanzas 9. XML Stanzas
Once XML streams in both directions have been authenticated and (if After Stream Encryption (Section 5) if desired, Stream Authentication
desired) encrypted, XML stanzas can be sent over the streams. Three (Section 6), and Resource Binding (Section 7) if necessary, XML
kinds of XML stanza are defined for the 'jabber:client' and stanzas can be sent over the streams. Three kinds of XML stanza are
'jabber:server' namespaces: <message/>, <presence/>, and <iq/>. In defined for the 'jabber:client' and 'jabber:server' namespaces:
addition, there are five common attributes for these kinds of stanza. <message/>, <presence/>, and <iq/>. In addition, there are five
These common attributes and the basic semantics of the three stanza common attributes for these kinds of stanza. These common attributes,
kinds are defined herein; more detailed information regarding the as well as the basic semantics of the three stanza kinds, are defined
syntax of XML stanzas in relation to instant messaging and presence herein; more detailed information regarding the syntax of XML stanzas
applications is provided in XMPP IM [20]. in relation to instant messaging and presence applications is
provided in XMPP IM [21].
8.1 Common Attributes 9.1 Common Attributes
The following five attributes are common to message, presence, and IQ The following five attributes are common to message, presence, and IQ
stanzas: stanzas:
8.1.1 to 9.1.1 to
The 'to' attribute specifies the JID of the intended recipient for The 'to' attribute specifies the JID of the intended recipient for
the stanza. the stanza.
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) SHOULD NOT possess a 'to' attribute. broadcasting to other entities) SHOULD NOT possess a 'to' attribute.
In the 'jabber:server' namespace, a stanza MUST possess a 'to' In the 'jabber:server' namespace, a stanza MUST possess a 'to'
attribute; if a server receives a stanza that does not meet this attribute; if a server receives a stanza that does not meet this
restriction, it MUST generate an <improper-addressing/> stream error restriction, it MUST generate an <improper-addressing/> stream error
condition and terminate both the XML stream and the underlying TCP condition and terminate both the XML stream and the underlying TCP
connection with the offending server. connection with the offending server.
If the value of the 'to' attribute is invalid or cannot be contacted, If the value of the 'to' attribute is invalid or cannot be contacted,
the entity discovering that fact (usually the sender's or recipient's the entity discovering that fact (usually the sender's or recipient's
server) MUST return an appropriate error to the sender. server) MUST return an appropriate error to the sender, setting the
'from' attribute of the error stanza to the value provided in the
'to' attribute of the offending stanza.
8.1.2 from 9.1.2 from
The 'from' attribute specifies the JID of the sender. The 'from' attribute specifies the JID of the sender.
In the 'jabber:client' namespace, a client MUST NOT include a 'from' When a server receives an XML stanza within the context of an
attribute on the stanzas it sends to a server; if a server receives authenticated stream qualified by the 'jabber:client' namespace, it
an XML stanza from a client and the stanza possesses a 'from' MUST do one of the following:
attribute, it MUST ignore the value of the 'from' attribute and MAY
return an error to the sender. When a client sends an XML stanza 1. validate that the value of the 'from' attribute provided by the
within the context of an authenticated stream, the server MUST stamp client is that of an authorized resource for the associated
the stanza with the full JID (<user@domain/resource>) of the entity
connected resource that generated the stanza as defined by the 2. add a 'from' address to the stanza whose value is the full JID
authzid provided in the SASL negotiation. If a client attempts to (<node@domain/resource>) determined by the server for the
send an XML stanza before the stream is authenticated, the server connected resource that generated the stanza (see Determination
SHOULD return a <not-authorized/> stream error to the client and then of Addresses (Section 3.6))
terminate both the XML stream and the underlying TCP connection.
If a client attempts to send an XML stanza for which the value of the
'from' attribute does not match one of the connected resources for
that entity, the server SHOULD return an <invalid-from/> stream error
to the client. If a client attempts to send an XML stanza over a
stream that is not yet authenticated, the server SHOULD return a
<not-authorized/> stream error to the client. If generated, both of
these conditions MUST result in closing of the stream and termination
of the underlying TCP connection; this helps to prevent a denial of
service attack launched from a rogue client.
In the 'jabber:server' namespace, a stanza MUST possess a 'from' In the 'jabber:server' namespace, a stanza MUST possess a 'from'
attribute; if a server receives a stanza that does not meet this attribute; if a server receives a stanza that does not meet this
restriction, it MUST generate an <improper-addressing/> stream error restriction, it MUST generate an <improper-addressing/> stream error
condition. Furthermore, the domain identifier portion of the JID condition. Furthermore, the domain identifier portion of the JID
contained in the 'from' attribute MUST match the hostname of the contained in the 'from' attribute MUST match the hostname (or any
sending server (or any validated domain) as communicated in the SASL validated domain) of the sending server as communicated in the SASL
negotiation or dialback negotiation; if a server receives a stanza negotiation or dialback negotiation; if a server receives a stanza
that does not meet this restriction, it MUST generate a that does not meet this restriction, it MUST generate an
<nonmatching-hosts/> stream error condition. Both of these conditions <invalid-from/> stream error condition. Both of these conditions MUST
MUST result in closing of the stream and termination of the result in closing of the stream and termination of the underlying TCP
underlying TCP connection. connection; this helps to prevent a denial of service attack launched
from a rogue server.
8.1.3 id 9.1.3 id
The optional 'id' attribute MAY be used by a sending entity for The optional 'id' attribute MAY be used by a sending entity for
internal tracking of stanzas that it sends and receives (especially internal tracking of stanzas that it sends and receives (especially
for tracking the request-response interaction inherent in the use of for tracking the request-response interaction inherent in the
IQ stanzas). The value of the 'id' attribute is NOT REQUIRED to be semantics of IQ stanzas). The value of the 'id' attribute is NOT
unique either globally, within a domain, or within a stream. The REQUIRED to be unique either globally, within a domain, or within a
semantics of IQ stanzas impose additional restrictions; see the IQ stream. The semantics of IQ stanzas impose additional restrictions;
Semantics (Section 8.2.3) section of this document. see IQ Semantics (Section 9.2.3).
8.1.4 type 9.1.4 type
The 'type' attribute specifies detailed information about the purpose The 'type' attribute specifies detailed information about the purpose
or context of the message, presence, or IQ stanza. The particular or context of the message, presence, or IQ stanza. The particular
allowable values for the 'type' attribute vary depending on whether allowable values for the 'type' attribute vary depending on whether
the stanza is a message, presence, or IQ; the values for message and the stanza is a message, presence, or IQ; the values for message and
presence stanzas are specific to instant messaging and presence presence stanzas are specific to instant messaging and presence
applications and therefore are defined in XMPP IM [20], whereas the applications and therefore are defined in XMPP IM [21], whereas the
values for IQ stanzas specify the role of an IQ stanza in a values for IQ stanzas specify the role of an IQ stanza in a
structured request-response "conversation" and thus are described structured request-response "conversation" and thus are defined under
under IQ Semantics (Section 8.2.3) below. The only 'type' value IQ Semantics (Section 9.2.3) below. The only 'type' value common to
common to all three stanzas is "error"; see Stanza Errors (Section all three stanzas is "error", for which see Stanza Errors (Section
8.3). 9.3).
8.1.5 xml:lang 9.1.5 xml:lang
A stanza SHOULD possess an 'xml:lang' attribute (as defined in A stanza SHOULD possess an 'xml:lang' attribute (as defined in
Section 2.12 of the XML specification [1]) if the stanza contains XML Section 2.12 of the XML specification [1]) if the stanza contains XML
character data that is intended to be presented to a human user (as character data that is intended to be presented to a human user (as
explained in RFC 2277 [14], "internationalization is for humans"). explained in RFC 2277 [15], "internationalization is for humans").
The value of the 'xml:lang' attribute specifies the default language The value of the 'xml:lang' attribute specifies the default language
of any such XML character data, which MAY be overridden by the of any such human-readable XML character data, which MAY be
'xml:lang' attribute of a specific child element. The value of the overridden by the 'xml:lang' attribute of a specific child element.
attribute MUST be an NMTOKEN and MUST conform to the format defined If a stanza does not possess an 'xml:lang' attribute, an
in RFC 3066 [15]. implementation MUST assume that the default language is that
specified for the stream as defined under Stream Attributes (Section
4.2) above. The value of the 'xml:lang' attribute MUST be an NMTOKEN
and MUST conform to the format defined in RFC 3066 [16].
8.2 Basic Semantics 9.2 Basic Semantics
8.2.1 Message Semantics 9.2.1 Message Semantics
The <message/> stanza kind can be seen as a "push" mechanism whereby The <message/> stanza kind can be seen as a "push" mechanism whereby
one entity pushes information to another entity, similar to the one entity pushes information to another entity, similar to the
communications that occur in a system such as email. All message communications that occur in a system such as email. All message
stanzas SHOULD possess a 'to' attribute that specifies the intended stanzas SHOULD possess a 'to' attribute that specifies the intended
recipient of the message; upon receiving such a stanza, a server recipient of the message; upon receiving such a stanza, a server
SHOULD route or deliver it to the intended recipient (see Server SHOULD route or deliver it to the intended recipient (see Server
Rules for Handling XML Stanzas (Section 13) for general routing and Rules for Handling XML Stanzas (Section 14) for general routing and
delivery rules related to XML stanzas). delivery rules related to XML stanzas).
8.2.2 Presence Semantics 9.2.2 Presence Semantics
The <presence/> element can be seen as a basic broadcast or The <presence/> element can be seen as a basic broadcast or
"publish-subscribe" mechanism, whereby multiple entities receive "publish-subscribe" mechanism, whereby multiple entities receive
information (in this case, presence information) about an entity to information (in this case, presence information) about an entity to
which they have subscribed. In general, a publishing entity SHOULD which they have subscribed. In general, a publishing entity SHOULD
send a presence stanza with no 'to' attribute, in which case the send a presence stanza with no 'to' attribute, in which case the
server to which the entity is connected SHOULD broadcast or multiplex server to which the entity is connected SHOULD broadcast or multiplex
that stanza to all subscribing entities. However, a publishing entity that stanza to all subscribing entities. However, a publishing entity
MAY also send a presence stanza with a 'to' attribute, in which case MAY also send a presence stanza with a 'to' attribute, in which case
the server SHOULD route or deliver that stanza to the intended the server SHOULD route or deliver that stanza to the intended
recipient. See Server Rules for Handling XML Stanzas (Section 13) for recipient. See Server Rules for Handling XML Stanzas (Section 14) for
general routing and delivery rules related to XML stanzas, and XMPP general routing and delivery rules related to XML stanzas, and XMPP
IM [20] for presence-specific rules in the context of an instant IM [21] for presence-specific rules in the context of an instant
messaging and presence application. messaging and presence application.
8.2.3 IQ Semantics 9.2.3 IQ Semantics
Info/Query, or IQ, is a request-response mechanism, similar in some Info/Query, or IQ, is a request-response mechanism, similar in some
ways to HTTP [21]. The semantics of IQ enable an entity to make a ways to HTTP [22]. The semantics of IQ enable an entity to make a
request of, and receive a response from, another entity. The data request of, and receive a response from, another entity. The data
content of the request and response is defined by the namespace content of the request and response is defined by the namespace
declaration of a direct child element of the IQ element, and the declaration of a direct child element of the IQ element, and the
interaction is tracked by the requesting entity through use of the interaction is tracked by the requesting entity through use of the
'id' attribute. Thus IQ interactions follow a common pattern of 'id' attribute. Thus IQ interactions follow a common pattern of
structured data exchange such as get/result or set/result (although structured data exchange such as get/result or set/result (although
an error may be returned in response to a request if appropriate): an error may be returned in reply to a request if appropriate):
Requesting Responding Requesting Responding
Entity Entity Entity Entity
---------- ---------- ---------- ----------
| | | |
| <iq type='get' id='1'> | | <iq type='get' id='1'> |
| ------------------------> | | ------------------------> |
| | | |
| <iq type='result' id='1'> | | <iq type='result' id='1'> |
| <------------------------ | | <------------------------ |
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requirements. requirements.
* set -- The stanza provides required data, sets new values, or * set -- The stanza provides required data, sets new values, or
replaces existing values. replaces existing values.
* result -- The stanza is a response to a successful get or set * result -- The stanza is a response to a successful get or set
request. request.
* error -- An error has occurred regarding processing or * error -- An error has occurred regarding processing or
delivery of a previously-sent get or set (see Stanza Errors delivery of a previously-sent get or set (see Stanza Errors
(Section 8.3)). (Section 9.3)).
3. An entity that receives an IQ request of type "get" or "set" MUST 3. An entity that receives an IQ request of type "get" or "set" MUST
reply with an IQ response of type "result" or "error" (which reply with an IQ response of type "result" or "error" (which
response MUST preserve the 'id' attribute of the request). response MUST preserve the 'id' attribute of the request).
4. An entity that receives a stanza of type "result" or "error" MUST 4. An entity that receives a stanza of type "result" or "error" MUST
NOT respond to the stanza by sending a further IQ response of NOT respond to the stanza by sending a further IQ response of
type "result" or "error"; however, as shown above, the requesting type "result" or "error"; however, as shown above, the requesting
entity MAY send another request (e.g., an IQ of type "set" in entity MAY send another request (e.g., an IQ of type "set" in
order to provide required information discovered through a get/ order to provide required information discovered through a get/
result pair). result pair).
5. An IQ stanza of type "get" or "set" MUST contain one and only one 5. An IQ stanza of type "get" or "set" MUST contain one and only one
child element (properly-namespaced as defined in XMPP IM [20]) child element (properly-namespaced as defined in XMPP IM [21])
that specifies the semantics of the particular request or that specifies the semantics of the particular request or
response. response.
6. An IQ stanza of type "result" MUST include zero or one child 6. An IQ stanza of type "result" MUST include zero or one child
elements. elements.
7. An IQ stanza of type "error" SHOULD include the child element 7. An IQ stanza of type "error" SHOULD include the child element
contained in the associated "get" or "set" and MUST include an contained in the associated "get" or "set" and MUST include an
<error/> child; for details, see Stanza Errors (Section 8.3). <error/> child; for details, see Stanza Errors (Section 9.3).
8.3 Stanza Errors 9.3 Stanza Errors
Stanza-related errors are handled in a manner similar to stream Stanza-related errors are handled in a manner similar to stream
errors (Section 4.6), except that hints are also provided to the errors (Section 4.6). However, stanza errors are not unrecoverable,
receiving application regarding actions to take in response to the as stream errors are; therefore error stanzas include hints regarding
actions that the original sender can take in order to remedy the
error. error.
8.3.1 Rules 9.3.1 Rules
The following rules apply to stanza-related errors: The following rules apply to stanza-related errors:
o The receiving or processing entity that detects an error condition o The receiving or processing entity that detects an error condition
in relation to a stanza MUST return to the sending entity a stanza in relation to a stanza MUST return to the sending entity a stanza
of the same kind (message, presence, or IQ) whose 'type' attribute of the same kind (message, presence, or IQ) whose 'type' attribute
is set to a value of "error". is set to a value of "error" (such a stanza is called an "error
stanza" herein).
o The entity that generates a stanza of type "error" SHOULD (but is o The entity that generates an error stanza SHOULD (but is NOT
NOT REQUIRED to) include the original XML sent so that the sender REQUIRED to) include the original XML sent so that the sender can
can inspect and if necessary correct the XML before attempting to inspect and if necessary correct the XML before attempting to
resend. resend.
o A stanza whose 'type' attribute has a value of "error" MUST o An error stanza MUST contain an <error/> child element.
contain an <error/> child element.
o An <error/> child MUST NOT be included if the 'type' attribute has o An <error/> child MUST NOT be included if the 'type' attribute has
a value other than "error" (or if there is no 'type' attribute). a value other than "error" (or if there is no 'type' attribute).
o An entity that receives a stanza whose 'type' attribute has a o An entity that receives an error stanza MUST NOT respond to the
value of "error" MUST NOT respond to the stanza with a further stanza with a further error stanza; this helps to prevent looping.
stanza of type "error"; this helps to prevent looping.
8.3.2 Syntax 9.3.2 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'>
[RECOMMENDED to include sender XML here] [RECOMMENDED to include sender XML here]
<error type='error-type'> <error type='error-type'>
<defined-condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> <defined-condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<text xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'> <text xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
OPTIONAL descriptive text OPTIONAL descriptive text
</text> </text>
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o modify -- retry after changing the data sent o modify -- retry after changing the data sent
o auth -- retry after providing credentials o auth -- retry after providing credentials
o wait -- retry after waiting (the error is temporary) o wait -- retry after waiting (the error is temporary)
The <error/> element: The <error/> element:
o MUST contain a child element corresponding to one of the defined o MUST contain a child element corresponding to one of the defined
stanza error conditions defined below; this element MUST be stanza error conditions specified below; this element MUST be
qualified by the 'urn:ietf:params:xml:ns:xmpp-stanzas' namespace qualified by the 'urn:ietf:params:xml:ns:xmpp-stanzas' namespace.
o MAY contain a <text/> child containing CDATA that describes the o MAY contain a <text/> child containing CDATA that describes the
error in more detail; this element MUST be qualified by the error in more detail; this element MUST be qualified by the
'urn:ietf:params:xml:ns:xmpp-stanzas' namespace and SHOULD possess 'urn:ietf:params:xml:ns:xmpp-stanzas' namespace and SHOULD possess
an 'xml:lang' attribute an 'xml:lang' attribute.
o MAY contain a child element for an application-specific error o MAY contain a child element for an application-specific error
condition; this element MUST be qualified by an condition; this element MUST be qualified by an
application-defined namespace, and its structure is defined by application-defined namespace, and its structure is defined by
that namespace that namespace.
The <text/> element is OPTIONAL. If included, it SHOULD be used only The <text/> element is OPTIONAL. If included, it SHOULD be used only
to provide descriptive or diagnostic information that supplements the to provide descriptive or diagnostic information that supplements the
meaning of a defined condition or application-specific condition. It meaning of a defined condition or application-specific condition. It
SHOULD NOT be interpreted programmatically by an application. It SHOULD NOT be interpreted programmatically by an application. It
SHOULD NOT be used as the error message presented to user, but MAY be SHOULD NOT be used as the error message presented to a user, but MAY
shown in addition to the error message associated with the included be shown in addition to the error message associated with the
condition element (or elements). included condition element (or elements).
Note: the XML namespace name 'urn:ietf:params:xml:ns:xmpp-stanzas' Note: the XML namespace name 'urn:ietf:params:xml:ns:xmpp-stanzas'
that qualifies the descriptive element adheres to the format defined that qualifies the descriptive element adheres to the format defined
in The IETF XML Registry [23]. in The IETF XML Registry [24].
8.3.3 Defined Conditions 9.3.3 Defined Conditions
The following stanza-related error conditions are defined for use in The following stanza-related error conditions are defined for use in
stanza errors. stanza errors.
o <bad-request/> -- the sender has sent XML that is malformed or o <bad-request/> -- the sender has sent XML that is malformed or
that cannot be processed (e.g., a client-generated stanza includes that cannot be processed (e.g., an IQ stanza that includes an
a 'from' address, or an IQ stanza includes an unrecognized value unrecognized value of the 'type' attribute); the associated error
of the 'type' attribute); the associated error type SHOULD be type SHOULD be "modify".
"modify".
o <conflict/> -- access cannot be granted because an existing o <conflict/> -- access cannot be granted because an existing
resource or session exists with the same name or address; the resource or session exists with the same name or address; the
associated error type SHOULD be "cancel". associated error type SHOULD be "cancel".
o <feature-not-implemented/> -- the feature requested is not o <feature-not-implemented/> -- the feature requested is not
implemented by the recipient or server and therefore cannot be implemented by the recipient or server and therefore cannot be
processed; the associated error type SHOULD be "cancel". processed; the associated error type SHOULD be "cancel".
o <forbidden/> -- the requesting entity does not possess the o <forbidden/> -- the requesting entity does not possess the
required permissions to perform the action; the associated error required permissions to perform the action; the associated error
type SHOULD be "auth". type SHOULD be "auth".
o <gone/> -- the recipient or server can no longer be contacted at
this address (the error stanza MAY contain a new address in the
CDATA of the <gongone/> element); the associated error type SHOULD
be "modify".
o <internal-server-error/> -- the server could not process the o <internal-server-error/> -- the server could not process the
stanza because of a misconfiguration or an otherwise-undefined stanza because of a misconfiguration or an otherwise-undefined
internal server error; the associated error type SHOULD be "wait". internal server error; the associated error type SHOULD be "wait".
o <item-not-found/> -- the addressed JID or item requested cannot be o <item-not-found/> -- the addressed JID or item requested cannot be
found; the associated error type SHOULD be "cancel". found; the associated error type SHOULD be "cancel".
o <jid-malformed/> -- the value of the 'to' attribute in the o <jid-malformed/> -- the value of the 'to' attribute in the
sender's stanza does not adhere to the syntax defined in sender's stanza does not adhere to the syntax defined in
Addressing Scheme (Section 3); the associated error type SHOULD be Addressing Scheme (Section 3); the associated error type SHOULD be
"modify". "modify".
o <not-allowed/> -- the recipient does not allow any entity to o <not-acceptable/> -- the recipient or server understands the
perform the action; the associated error type SHOULD be "cancel". request but is refusing to process it because it does not meet
criteria defined by the recipient or server (e.g., a local policy
o <payment-required/> -- the user is not authorized to access the regarding acceptable words in messages); the associated error type
requested service because payment is required; the associated SHOULD be "cancel".
error type SHOULD be "auth".
o <recipient-unavailable/> -- the specific recipient requested is o <not-allowed/> -- the recipient or server does not allow any
currently unavailable; the associated error type SHOULD be "wait". entity to perform the action; the associated error type SHOULD be
"cancel".
o <registration-required/> -- the user is not authorized to access o <payment-required/> -- the requesting entity is not authorized to
the requested service because registration is required; the access the requested service because payment is required; the
associated error type SHOULD be "auth". associated error type SHOULD be "auth".
o <recipient-unavailable/> -- the intended recipient is temporarily
unavailable; the associated error type SHOULD be "wait" (note: an
application MUST NOT return this error if doing so would provide
information about the intended recipient's network availability to
an entity that is not authorized to know such information).
o <redirect/> -- the recipient or server is redirecting requests for
this information to another entity, usually temporarily (the error
stanza MAY contain a new address in the CDATA of the <redirect/>
element); the associated error type SHOULD be "modify".
o <registration-required/> -- the requesting entity is not
authorized to access the requested service because registration is
required; the associated error type SHOULD be "auth".
o <remote-server-not-found/> -- a remote server or service specified o <remote-server-not-found/> -- a remote server or service specified
as part or all of the JID of the intended recipient does not as part or all of the JID of the intended recipient does not
exist; the associated error type SHOULD be "cancel". exist; the associated error type SHOULD be "cancel".
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 error contacted within a reasonable amount of time; the associated error
type SHOULD be "wait". type SHOULD be "wait".
o <resource-constraint/> -- the server is resource-constrained and o <resource-constraint/> -- the server or recipient lacks the system
is unable to service the request; the associated error type SHOULD resources necessary to service the request; the associated error
be "wait". type SHOULD be "wait".
o <service-unavailable/> -- the service requested is currently o <service-unavailable/> -- the server or recipient does not
unavailable on the server; the associated error type SHOULD be currently provide the requested service; the associated error type
"cancel". SHOULD be "cancel".
o <subscription-required/> -- the user is not authorized to access o <subscription-required/> -- the requesting entity is not
the requested service because a subscription is required; the authorized to access the requested service because a subscription
associated error type SHOULD be "auth". is required; the associated error type SHOULD be "auth".
o <undefined-condition/> -- the error condition is not one of those o <undefined-condition/> -- the error condition is not one of those
defined by the other conditions in this list; any error type may defined by the other conditions in this list; any error type may
be associated with this condition, and it SHOULD be used only in be associated with this condition, and it SHOULD be used only in
conjunction with an application-specific condition. conjunction with an application-specific condition.
o <unexpected-request/> -- the recipient understood the request but o <unexpected-request/> -- the recipient or server understood the
was not expecting it at this time (e.g., the request was out of request but was not expecting it at this time (e.g., the request
order); the associated error type SHOULD be "wait". was out of order); the associated error type SHOULD be "wait".
8.3.4 Application-Specific Conditions 9.3.4 Application-Specific Conditions
As noted, an application MAY provide application-specific stanza As noted, an application MAY provide application-specific stanza
error information by including a properly-namespaced child in the error information by including a properly-namespaced child in the
error element. The application-specific element SHOULD supplement or error element. The application-specific element SHOULD supplement or
further qualify a defined element. Thus the <error/> element will further qualify a defined element. Thus the <error/> element will
contain two or three child elements: contain two or three child elements:
<iq type='error' id='some-id'> <iq type='error' id='some-id'>
<error type='modify'> <error type='modify'>
<bad-request xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> <bad-request xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<too-many-parameters xmlns='application-ns'/> <too-many-parameters xmlns='application-ns'/>
</error> </error>
</iq> </iq>
<message type='error' id='another-id'> <message type='error' id='another-id'>
<error type='modify'> <error type='modify'>
<undefined-condition xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> <undefined-condition
<text xml:lang='en' xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'> xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
Some special application diagnostic information! <text xml:lang='en'
xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
Some special application diagnostic information...
</text> </text>
<special-application-condition xmlns='application-ns'/> <special-application-condition xmlns='application-ns'/>
</error> </error>
</message> </message>
9. XML Usage within XMPP 10. XML Usage within XMPP
9.1 Restrictions 10.1 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 structured information in close to real
close to real time. Because XMPP does not require the parsing of time. Because XMPP does not require the parsing of arbitrary and
arbitrary and complete XML documents, there is no requirement that complete XML documents, there is no requirement that XMPP needs to
XMPP needs to support the full XML specification [1]. In particular, support the full XML specification [1]. In particular, the following
the following restrictions apply. restrictions apply.
With regard to XML generation, an XMPP implementation MUST NOT inject With regard to XML generation, an XMPP implementation MUST NOT inject
into an XML stream any of the following: into an XML stream any of the following:
o comments (as defined in Section 2.5 of the XML specification [1]) o comments (as defined in Section 2.5 of the XML specification [1])
o processing instructions (Section 2.6) o processing instructions (Section 2.6 therein)
o internal or external DTD subsets (Section 2.8) o internal or external DTD subsets (Section 2.8 therein)
o internal or external entity references (Section 4.2) with the o internal or external entity references (Section 4.2 therein) with
exception of predefined entities (Section 4.6) the exception of predefined entities (Section 4.6 therein)
o character data or attribute values containing unescaped characters o character data or attribute values containing unescaped characters
that map to the predefined entities (Section 4.6); such characters that map to the predefined entities (Section 4.6 therein); such
MUST be escaped characters MUST be escaped
With regard to XML processing, if an XMPP implementation receives With regard to XML processing, if an XMPP implementation receives
such restricted XML data, it MUST ignore the data. such restricted XML data, it MUST ignore the data.
9.2 XML Namespace Names and Prefixes 10.2 XML Namespace Names and Prefixes
XML Namespaces [10] are used within all XMPP-compliant XML to create XML Namespaces [10] 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 allowable XML to be structurally mixed
data element within XMPP. Rules for XML namespace names and prefixes with any data element within XMPP. Rules for XML namespace names and
are defined below. prefixes are defined in the following subsections.
9.2.1 Stream Namespace 10.2.1 Streams Namespace
A stream namespace declaration is REQUIRED in both XML stream A streams namespace declaration is REQUIRED in all XML stream
headers. The name of the stream namespace MUST be 'http:// headers. The name of the streams namespace MUST be 'http://
etherx.jabber.org/streams'. The element names of the <stream/> etherx.jabber.org/streams'. The element names of the <stream/>
element and its <features/> and <error/> children MUST be qualified element and its <features/> and <error/> children MUST be qualified
by the stream namespace prefix in all instances. An implementation by the streams namespace prefix in all instances. An implementation
SHOULD generate only the 'stream:' prefix for these elements, and for SHOULD generate only the 'stream:' prefix for these elements, and for
historical reasons MAY accept only the 'stream:' prefix. historical reasons MAY accept only the 'stream:' prefix.
9.2.2 Default Namespace 10.2.2 Default Namespace
A default namespace declaration is REQUIRED and is used in both XML A default namespace declaration is REQUIRED and is used in all XML
streams in order to define the allowable first-level children of the streams in order to define the allowable first-level children of the
root stream element. This namespace declaration MUST be the same for root stream element. This namespace declaration MUST be the same for
the initiating stream and the responding stream so that both streams the initial stream and the response stream so that both streams are
are qualified consistently. The default namespace declaration applies qualified consistently. The default namespace declaration applies to
to the stream and all stanzas sent within a stream (unless explicitly the stream and all stanzas sent within a stream (unless explicitly
qualified by another namespace, or by the prefix of the stream qualified by another namespace, or by the prefix of the streams
namespace or the dialback namespace). namespace or the dialback namespace).
A server implementation MUST support the following two default A server implementation MUST support the following two default
namespaces (for historical reasons, some implementations MAY support namespaces (for historical reasons, some implementations MAY support
only these two default namespaces): 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
skipping to change at page 55, line 45 skipping to change at page 58, line 45
namespaces other than 'jabber:client' and 'jabber:server'. namespaces other than 'jabber:client' and 'jabber:server'.
Note: the 'jabber:client' and 'jabber:server' namespaces are nearly Note: the 'jabber:client' and 'jabber:server' namespaces are nearly
identical but are used in different contexts (client-to-server identical but are used in different contexts (client-to-server
communications for 'jabber:client' and server-to-server communications for 'jabber:client' and server-to-server
communications for 'jabber:server'). The only difference between the communications for 'jabber:server'). The only difference between the
two is that the 'to' and 'from' attributes are OPTIONAL on stanzas two is that the 'to' and 'from' attributes are OPTIONAL on stanzas
sent within 'jabber:client', whereas they are REQUIRED on stanzas sent within 'jabber:client', whereas they are REQUIRED on stanzas
sent within 'jabber:server'. If a compliant implementation accepts a sent within 'jabber:server'. If a compliant implementation accepts a
stream that is qualified by the 'jabber:client' or 'jabber:server' stream that is qualified by the 'jabber:client' or 'jabber:server'
namespace, it MUST support the common attributes (Section 8.1) and namespace, it MUST support the common attributes (Section 9.1) and
basic semantics (Section 8.2) of all three core stanza kinds basic semantics (Section 9.2) of all three core stanza kinds
(message, presence, and IQ). (message, presence, and IQ).
9.2.3 Dialback Namespace 10.2.3 Dialback Namespace
A dialback namespace declaration is REQUIRED for all elements used in A dialback namespace declaration is REQUIRED for all elements used in
server dialback. The name of the dialback namespace MUST be server dialback (Section 8). The name of the dialback namespace MUST
'jabber:server:dialback'. All elements qualified by this namespace be 'jabber:server:dialback'. All elements qualified by this namespace
MUST be prefixed. An implementation SHOULD generate only the 'db:' MUST be prefixed. An implementation SHOULD generate only the 'db:'
prefix for such elements and MAY accept only the 'db:' prefix. prefix for such elements and MAY accept only the 'db:' prefix.
9.3 Validation 10.3 Validation
Except as noted with regard to 'to' and 'from' addresses for stanzas Except as noted with regard to 'to' and 'from' addresses for stanzas
within the 'jabber:server' namespace, a server is not responsible for within the 'jabber:server' namespace, a server is not responsible for
validating the XML elements forwarded to a client or another server; validating the XML elements forwarded to a client or another server;
an implementation MAY choose to provide only validated data elements an implementation MAY choose to provide only validated data elements
but is NOT REQUIRED to do so (although an implementation MUST NOT but is NOT REQUIRED to do so (although an implementation MUST NOT
accept XML that is not well-formed). Clients SHOULD NOT rely on the accept XML that is not well-formed). Clients SHOULD NOT rely on the
ability to send data which does not conform to the schemas, and ability to send data which does not conform to the schemas, and
SHOULD ignore any non-conformant elements or attributes on the SHOULD ignore any non-conformant elements or attributes on the
incoming XML stream. Validation of XML streams and stanzas is NOT incoming XML stream. Validation of XML streams and stanzas is NOT
REQUIRED or recommended, and schemas are included herein for REQUIRED or recommended, and schemas are included herein for
descriptive purposes only. descriptive purposes only.
9.4 Inclusion of Text Declaration 10.4 Inclusion of Text Declaration
Implementations SHOULD send a text declaration before sending a Implementations SHOULD send a text declaration before sending a
stream header. Applications MUST follow the rules in the XML stream header. Applications MUST follow the rules in the XML
specification [1] regarding the circumstances under which a text specification [1] regarding the circumstances under which a text
declaration is included. declaration is included.
9.5 Character Encoding 10.5 Character Encoding
Implementations MUST support the UTF-8 (RFC 2279 [16]) transformation Implementations MUST support the UTF-8 (RFC 2279 [17]) transformation
of Universal Character Set (ISO/IEC 10646-1 [17]) characters, as of Universal Character Set (ISO/IEC 10646-1 [18]) characters, as
required by RFC 2277 [14]. Implementations MUST NOT attempt to use required by RFC 2277 [15]. Implementations MUST NOT attempt to use
any other encoding. any other encoding.
10. IANA Considerations 11. IANA Considerations
10.1 XML Namespace Name for TLS Data 11.1 XML Namespace Name for TLS Data
A URN sub-namespace for TLS-related data in the Extensible Messaging A URN sub-namespace for TLS-related data in the Extensible Messaging
and Presence Protocol (XMPP) is defined as follows. and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-tls URI: urn:ietf:params:xml:ns:xmpp-tls
Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for TLS-related data in Description: This is the XML namespace name for TLS-related data in
the Extensible Messaging and Presence Protocol (XMPP) as defined the Extensible Messaging and Presence Protocol (XMPP) as defined
by [RFCXXXX]. by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org> Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
10.2 XML Namespace Name for SASL Data 11.2 XML Namespace Name for SASL Data
A URN sub-namespace for SASL-related data in the Extensible Messaging A URN sub-namespace for SASL-related data in the Extensible Messaging
and Presence Protocol (XMPP) is defined as follows. and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-sasl URI: urn:ietf:params:xml:ns:xmpp-sasl
Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for SASL-related data in Description: This is the XML namespace name for SASL-related data in
the Extensible Messaging and Presence Protocol (XMPP) as defined the Extensible Messaging and Presence Protocol (XMPP) as defined
by [RFCXXXX]. by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org> Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
10.3 XML Namespace Name for Stream Errors 11.3 XML Namespace Name for Stream Errors
A URN sub-namespace for stream-related error data in the Extensible A URN sub-namespace for stream-related error data in the Extensible
Messaging and Presence Protocol (XMPP) is defined as follows. Messaging and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-streams URI: urn:ietf:params:xml:ns:xmpp-streams
Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for stream-related error Description: This is the XML namespace name for stream-related error
data in the Extensible Messaging and Presence Protocol (XMPP) as data in the Extensible Messaging and Presence Protocol (XMPP) as
defined by [RFCXXXX]. defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org> Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
10.4 XML Namespace Name for Stanza Errors 11.4 XML Namespace Name for Resource Binding
A URN sub-namespace for resource binding in the Extensible Messaging
and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-bind
Specification: [RFCXXXX]
Description: This is the XML namespace name for resource binding in
the Extensible Messaging and Presence Protocol (XMPP) as defined
by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
11.5 XML Namespace Name for Stanza Errors
A URN sub-namespace for stanza-related error data in the Extensible A URN sub-namespace for stanza-related error data in the Extensible
Messaging and Presence Protocol (XMPP) is defined as follows. Messaging and Presence Protocol (XMPP) is defined as follows.
URI: urn:ietf:params:xml:ns:xmpp-stanzas URI: urn:ietf:params:xml:ns:xmpp-stanzas
Specification: [RFCXXXX] Specification: [RFCXXXX]
Description: This is the XML namespace name for stanza-related error Description: This is the XML namespace name for stanza-related error
data in the Extensible Messaging and Presence Protocol (XMPP) as data in the Extensible Messaging and Presence Protocol (XMPP) as
defined by [RFCXXXX]. defined by [RFCXXXX].
Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org> Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>
10.5 Nodeprep Profile of Stringprep 11.6 Nodeprep Profile of Stringprep
The Nodeprep profile of stringprep is defined in Appendix A (Appendix The Nodeprep profile of stringprep is defined under Nodeprep
A) of this document. If and when this document becomes an RFC, the (Appendix A). The IANA registers Nodeprep in the stringprep profile
Nodeprep profile shall be registered in the stringprep profile registry.
registry maintained by the IANA [5].
Name of this profile: Name of this profile:
Nodeprep Nodeprep
RFC in which the profile is defined: RFC in which the profile is defined:
This document [RFCXXXX]
Indicator whether or not this is the newest version of the profile: Indicator whether or not this is the newest version of the profile:
This is the first version of Nodeprep This is the first version of Nodeprep
10.6 Resourceprep Profile of Stringprep 11.7 Resourceprep Profile of Stringprep
The Resourceprep profile of stringprep is defined in Appendix B The Resourceprep profile of stringprep is defined under Resourceprep
(Appendix B) of this document. If and when this document becomes an (Appendix B). The IANA registers Resourceprep in the stringprep
RFC, the Resourceprep profile shall be registered in the stringprep profile registry.
profile registry maintained by the IANA [5].
Name of this profile: Name of this profile:
Resourceprep Resourceprep
RFC in which the profile is defined: RFC in which the profile is defined:
This document [RFCXXXX]
Indicator whether or not this is the newest version of the profile: Indicator whether or not this is the newest version of the profile:
This is the first version of Resourceprep This is the first version of Resourceprep
10.7 Existing Registrations 11.8 GSSAPI Service Name
The IANA registers "xmpp" as a GSSAPI [18] service name, as defined The IANA registers "xmpp" as a GSSAPI [19] service name, as defined
under SASL Definition (Section 6.4). under SASL Definition (Section 6.3).
Additionally, the IANA registers "jabber-client" and "jabber-server" 11.9 Port Numbers
as keywords for TCP ports 5222 and 5269 respectively. These ports
SHOULD be used for client-to-server and server-to-server
communications respectively, but their use is NOT REQUIRED. The use
of the string "jabber" in these keywords is historical.
11. Internationalization Considerations The IANA currently registers "jabber-client" and "jabber-server" as
keywords for TCP ports 5222 and 5269 respectively. The IANA shall
change these registrations to "xmpp-client" and "xmpp-server"
respectively.
XML streams MUST be encoded in UTF-8 as specified under the Character These ports SHOULD be used for client-to-server and server-to-server
Encoding (Section 9.5) section of this document. As speficied under communications respectively, but their use is NOT REQUIRED.
xml:lang (Section 8.1.5), an XML stanza SHOULD include an 'xml:lang'
attribute if the stanza contains XML character data that is intended
to be presented to a human user. Servers MUST NOT modify or delete
'xml:lang' attributes from stanzas they receive from other entities.
12. Security Considerations 12. Internationalization Considerations
12.1 High Security XML streams MUST be encoded in UTF-8 as specified under Character
Encoding (Section 10.5). As specified under Stream Attributes
(Section 4.2), an XML stream SHOULD include an 'xml:lang' attribute
that is treated as the default language for any XML character data
sent over the stream that is intended to be presented to a human
user. As specified under xml:lang (Section 9.1.5), an XML stanza
SHOULD include an 'xml:lang' attribute if the stanza contains XML
character data that is intended to be presented to a human user. A
server SHOULD apply the default 'xml:lang' attribute to stanzas it
routes or delivers on behalf of connected entities, and MUST NOT
modify or delete 'xml:lang' attributes from stanzas it receives from
other entities.
13. Security Considerations
13.1 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.
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communicate with the service SHOULD be configured with the Root CA communicate with the service SHOULD be configured with the Root CA
certificate rather than the service certificate; this avoids problems certificate rather than the service certificate; this avoids problems
associated with simple comparison of service certificates. If a associated with simple comparison of service certificates. If a
self-signed service certificate is used, an entity SHOULD NOT trust self-signed service certificate is used, an entity SHOULD NOT trust
it if it is changed to another self-signed certificate or a it if it is changed to another self-signed certificate or a
certificate signed by an unrecognized authority. certificate signed by an unrecognized authority.
Implementations MUST support high security. Service provisioning Implementations MUST support high security. Service provisioning
SHOULD use high security, subject to local security policies. SHOULD use high security, subject to local security policies.
12.2 Client-to-Server Communications 13.2 Client-to-Server Communications
A compliant implementation MUST support both TLS and SASL for A compliant implementation MUST support both TLS and SASL for
connections to a server. connections to a server.
The TLS protocol for encrypting XML streams (defined under Stream The TLS protocol for encrypting XML streams (defined under Stream
Encryption (Section 5)) provides a reliable mechanism for helping to Encryption (Section 5)) provides a reliable mechanism for helping to
ensure the confidentiality and data integrity of data exchanged ensure the confidentiality and data integrity of data exchanged
between two entities. between two entities.
The SASL protocol for authenticating XML streams (defined under The SASL protocol for authenticating XML streams (defined under
Stream Authentication (Section 6)) provides a reliable mechanism for Stream Authentication (Section 6)) provides a reliable mechanism for
validating that a client connecting to a server is who it claims to validating that a client connecting to a server is who it claims to
be. be.
Client-to-server communications MUST NOT proceed until the DNS Client-to-server communications MUST NOT proceed until the DNS
hostname asserted by the server has been resolved. Such resolutions hostname asserted by the server has been resolved. Such resolutions
SHOULD first attempt to resolve the hostname using an SRV [19] SHOULD first attempt to resolve the hostname using an SRV [20]
Service of "jabber-client" and Proto of "tcp", resulting in resource Service of "xmpp-client" and Proto of "tcp", resulting in resource
records such as "_jabber-client._tcp.example.com." (the use of the records such as "_xmpp-client._tcp.example.com." (the use of the
string "jabber-client" for the service identifier is consistent with string "xmpp-client" for the service identifier is consistent with
the existing IANA registration). If the SRV lookup fails, the the IANA registration). If the SRV lookup fails, the fallback is a
fallback is a normal A lookup to determine the IP address, using the normal IPv4/IPv6 address record resolution to determine the IP
"jabber-client" port of 5222 assigned by the Internet Assigned address, using the "xmpp-client" port of 5222 assigned by the
Numbers Authority [5]. Internet Assigned Numbers Authority [5].
The IP address and method of access of clients MUST NOT be made The IP address and method of access of clients MUST NOT be made
available by a server, nor are any connections other than the available by a server, nor are any connections other than the
original server connection required. This helps to protect the original server connection required. This helps to protect the
client's server from direct attack or identification by third client's server from direct attack or identification by third
parties. parties.
12.3 Server-to-Server Communications 13.3 Server-to-Server Communications
A compliant implementation MUST support both TLS and SASL for A compliant implementation MUST support both TLS and SASL for
inter-domain communications. For historical reasons, a compliant inter-domain communications. For historical reasons, a compliant
implementation SHOULD also support Server Dialback (Section 7). implementation SHOULD also support Server Dialback (Section 8).
Because service provisioning is a matter of policy, it is OPTIONAL Because service provisioning is a matter of policy, it is OPTIONAL
for any given domain to communicate with other domains, and for any given domain to communicate with other domains, and
server-to-server communications MAY be disabled by the administrator server-to-server communications MAY be disabled by the administrator
of any given deployment. If a particular domain enables inter-domain of any given deployment. If a particular domain enables inter-domain
communications, it SHOULD enable high security. communications, it SHOULD enable high security.
Administrators may want to require use of SASL for server-to-server Administrators may want to require use of SASL for server-to-server
communications in order to ensure both authentication and communications in order to ensure both authentication and
confidentiality (e.g., on an organization's private network). confidentiality (e.g., on an organization's private network).
Compliant implementations SHOULD support SASL for this purpose. Compliant implementations SHOULD support SASL for this purpose.
Inter-domain connections MUST NOT proceed until the DNS hostnames Inter-domain connections MUST NOT proceed until the DNS hostnames
asserted by the servers have been resolved. Such resolutions MUST asserted by the servers have been resolved. Such resolutions MUST
first attempt to resolve the hostname using an SRV [19] Service of first attempt to resolve the hostname using an SRV [20] Service of
"jabber-server" and Proto of "tcp", resulting in resource records "xmpp-server" and Proto of "tcp", resulting in resource records such
such as "_jabber-server._tcp.example.com." (the use of the string as "_xmpp-server._tcp.example.com." (the use of the string
"jabber-server" for the service identifier is consistent with the "xmpp-server" for the service identifier is consistent with the IANA
existing IANA registration; note well that the "jabber-server" registration; note well that the "xmpp-server" service identifier
service identifier supersedes the earlier use of a "jabber" service supersedes the earlier use of a "jabber" service identifier, since
identifier, since the earlier usage did not conform to RFC 2782 the earlier usage did not conform to RFC 2782 [20]; implementations
[19]). If the SRV lookup fails, the fallback is a normal A lookup to desiring to be backwards compatible should continue to look for or
determine the IP address, using the "jabber-server" port of 5269 answer to the "jabber" service identifier as well). If the SRV lookup
fails, the fallback is a normal IPv4/IPv6 address record resolution
to determine the IP address, using the "xmpp-server" port of 5269
assigned by the Internet Assigned Numbers Authority [5]. assigned by the Internet Assigned Numbers Authority [5].
Server dialback helps protect against domain spoofing, thus making it Server dialback helps protect against domain spoofing, thus making it
more difficult to spoof XML stanzas. It is not a mechanism for more difficult to spoof XML stanzas. It is not a mechanism for
authenticating, securing, or encrypting streams between servers as is authenticating, securing, or encrypting streams between servers as is
done via SASL and TLS. Furthermore, it is susceptible to DNS done via SASL and TLS. Furthermore, it is susceptible to DNS
poisoning attacks unless DNSSec [28] is used, and even if the DNS poisoning attacks unless DNSSec [29] is used, and even if the DNS
information is accurate, dialback cannot protect from attacks where information is accurate, dialback cannot protect from attacks where
the attacker is capable of hijacking the IP address of the remote the attacker is capable of hijacking the IP address of the remote
domain. Domains requiring robust security SHOULD use TLS and SASL. If domain. Domains requiring robust security SHOULD use TLS and SASL. If
SASL is used for server-to-server authentication, dialback SHOULD NOT SASL is used for server-to-server authentication, dialback SHOULD NOT
be used since it is unnecessary. be used since it is unnecessary.
12.4 Order of Layers 13.4 Order of Layers
The order of layers in which protocols MUST be stacked is as follows: The order of layers in which protocols MUST be stacked is as follows:
1. TCP 1. TCP
2. TLS 2. TLS
3. SASL 3. SASL
4. XMPP 4. XMPP
The rationale for this order is that TCP is the base connection layer The rationale for this order is that TCP is the base connection layer
used by all of the protocols stacked on top of TCP, TLS is often used by all of the protocols stacked on top of TCP, TLS is often
provided at the operating system layer, SASL is often provided at the provided at the operating system layer, SASL is often provided at the
application layer, and XMPP is the application itself. application layer, and XMPP is the application itself.
12.5 Firewalls 13.5 Mandatory-to-Implement Technologies
Communications using XMPP normally occur over TCP sockets on port
5222 (client-to-server) or port 5269 (server-to-server), as
registered with the IANA [5] (see IANA Considerations (Section 10)).
Use of these well-known ports allows administrators to easily enable
or disable XMPP activity through existing and commonly-deployed
firewalls.
12.6 Mandatory to Implement Technologies
At a minimum, all implementations MUST support the following At a minimum, all implementations MUST support the following
mechanisms: mechanisms:
for authentication: the SASL DIGEST-MD5 mechanism for authentication: the SASL DIGEST-MD5 mechanism
for confidentiality: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA for confidentiality: TLS (using the TLS_RSA_WITH_3DES_EDE_CBC_SHA
cipher) cipher)
for both: TLS plus SASL EXTERNAL(using the for both: TLS plus SASL EXTERNAL(using the
TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher supporting client-side TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher supporting client-side
certificates) certificates)
12.7 Stringprep Profiles 13.6 Firewalls
XMPP defines two profiles of stringprep [9]: Nodeprep (Appendix A) Communications using XMPP normally occur over TCP sockets on port
(for node identifiers) and Resourceprep (Appendix B) (for resource 5222 (client-to-server) or port 5269 (server-to-server), as
identifiers). registered with the IANA [5] (see IANA Considerations (Section 11)).
Use of these well-known ports allows administrators to easily enable
or disable XMPP activity through existing and commonly-deployed
firewalls.
13.7 Use of base64 in SASL
Both the client and the server SHOULD verify any base64 [14] data
received during SASL negotiation. An implementation MUST reject (not
ignore) any characters that are not explicitly allowed by the base64
alphabet; this helps to guard against creation of a covert channel
that could be used to "leak" information. An implementation MUST NOT
break on invalid input and MUST reject any sequence of base64
characters containing the pad ('=') character if that character is
included as something other than the last character of the data (e.g.
"=AAA" or "BBBB=CCC"); this helps to guard against buffer overflow
attacks and other attacks on the implementation. Base encoding
visually hides otherwise easily recognized information, such as
passwords, but does not provide any computational confidentiality.
Base 64 encoding MUST follow the definition in Section 3 of RFC 3548
[14].
13.8 Stringprep Profiles
XMPP makes use of the Nameprep [6] profile of stringprep [7] for
processing of domain identifiers; for security considerations related
to Nameprep, refer to the appropriate section of RFC 3491.
In addition, XMPP defines two profiles of stringprep [7]: Nodeprep
(Appendix A) for node identifiers and Resourceprep (Appendix B) for
resource identifiers.
The Unicode and ISO/IEC 10646 repertoires have many characters that The Unicode and ISO/IEC 10646 repertoires have many characters that
look similar. In many cases, users of security protocols might do look similar. In many cases, users of security protocols might do
visual matching, such as when comparing the names of trusted third visual matching, such as when comparing the names of trusted third
parties. Because it is impossible to map similar-looking characters parties. Because it is impossible to map similar-looking characters
without a great deal of context such as knowing the fonts used, without a great deal of context such as knowing the fonts used,
stringprep does nothing to map similar-looking characters together stringprep does nothing to map similar-looking characters together
nor to prohibit some characters because they look like others. nor to prohibit some characters because they look like others.
A node identifier can be employed as one part of an entity's address A node identifier can be employed as one part of an entity's address
skipping to change at page 65, line 5 skipping to change at page 67, line 6
address in XMPP. One common usage is as the name for an instant address in XMPP. One common usage is as the name for an instant
messaging user's active session; another is as the nickname of a user messaging user's active session; another is as the nickname of a user
in a multi-user chat room; and many other kinds of entities could use in a multi-user chat room; and many other kinds of entities could use
resource identifiers as part of their addresses. The security of such resource identifiers as part of their addresses. The security of such
services could be compromised based on different interpretations of services could be compromised based on different interpretations of
the internationalized resource identifier; for example, a user could the internationalized resource identifier; for example, a user could
attempt to initiate multiple sessions with the same name, or a user attempt to initiate multiple sessions with the same name, or a user
could send a message to someone other than the intended recipient in could send a message to someone other than the intended recipient in
a multi-user chat room. a multi-user chat room.
13. Server Rules for Handling XML Stanzas 14. Server Rules for Handling XML Stanzas
Each server implementation will contain its own "delivery tree" for Each server implementation will contain its own "delivery tree" for
handling stanzas it receives. Such a tree determines whether a stanza handling stanzas it receives. Such a tree determines whether a stanza
needs to be routed to another domain, processed internally, or needs to be routed to another domain, processed internally, or
delivered to a resource associated with a connected node. The delivered to a resource associated with a connected node. The
following rules apply: following rules apply:
13.1 No 'to' Address 14.1 No 'to' Address
If the stanza possesses no 'to' attribute, the server SHOULD process If the stanza possesses no 'to' attribute, the server SHOULD process
it on behalf of the entity that sent it. Because all stanzas received it on behalf of the entity that sent it. Because all stanzas received
from other servers MUST possess a 'to' attribute, this rule applies from other servers MUST possess a 'to' attribute, this rule applies
only to stanzas received from a registered entity (such as a client) only to stanzas received from a registered entity (such as a client)
that is connected to the server. If the server receives a presence that is connected to the server. If the server receives a presence
stanza with no 'to' attribute, the server SHOULD broadcast it to the stanza with no 'to' attribute, the server SHOULD broadcast it to the
entities that are subscribed to the sending entity's presence, if entities that are subscribed to the sending entity's presence, if
applicable (the semantics of presence broadcast for instant messaging applicable (the semantics of presence broadcast for instant messaging
and presence applications are defined in XMPP IM [20]). If the server and presence applications are defined in XMPP IM [21]). If the server
receives an IQ stanza of type "get" or "set" with no 'to' attribute receives an IQ stanza of type "get" or "set" with no 'to' attribute
and it understands the namespace that qualifies the content of the and it understands the namespace that qualifies the content of the
stanza, it MUST either process the stanza on behalf of sending entity stanza, it MUST either process the stanza on behalf of sending entity
(where the meaning of "process" is determined by the semantics of the (where the meaning of "process" is determined by the semantics of the
qualifying namespace) or return an error to the sending entity. qualifying namespace) or return an error to the sending entity.
13.2 Foreign Domain 14.2 Foreign Domain
If the hostname of the domain identifier portion of the JID contained If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute does not match one of the configured hostnames in the 'to' attribute does not match one of the configured hostnames
of the server itself or a subdomain thereof, the server SHOULD route of the server itself or a subdomain thereof, the server SHOULD route
the stanza to the foreign domain (subject to local service the stanza to the foreign domain (subject to local service
provisioning and security policies regarding inter-domain provisioning and security policies regarding inter-domain
communication). There are two possible cases: communication). There are two possible cases:
A server-to-server stream already exists between the two domains: The A server-to-server stream already exists between the two domains: The
sender's server routes the stanza to the authoritative server for sender's server routes the stanza to the authoritative server for
the foreign domain over the existing stream the foreign domain over the existing stream
There exists no server-to-server stream between the two domains: The There exists no server-to-server stream between the two domains: The
sender's server first (1) resolves the hostname of the foreign sender's server (1) resolves the hostname of the foreign domain
domain (as defined under Server-to-Server Communications (Section (as defined under Server-to-Server Communications (Section 13.3)),
12.3)), (2) negotiates a server-to-server stream between the two (2) negotiates a server-to-server stream between the two domains
domains, and (3) routes the stanza to the authoritative server for (as defined under Stream Encryption (Section 5) and Stream
the foreign domain over the newly-established stream Authentication (Section 6)), and (3) routes the stanza to the
authoritative server for the foreign domain over the
newly-established stream
If routing to the recipient's server is unsuccessful, the sender's If routing to the recipient's server is unsuccessful, the sender's
server MUST return an error to the sender; if the recipient's server server MUST return an error to the sender; if the recipient's server
can be contacted but delivery by the recipient's server to the can be contacted but delivery by the recipient's server to the
recipient is unsuccessful, the recipient's server MUST return an recipient is unsuccessful, the recipient's server MUST return an
error to the sender by way of the sender's server. error to the sender by way of the sender's server.
13.3 Subdomain 14.3 Subdomain
If the hostname of the domain identifier portion of the JID contained If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute matches a subdomain of one of the configured in the 'to' attribute matches a subdomain of one of the configured
hostnames of the server itself, the server MAY process the stanza hostnames of the server itself, the server MUST either process the
itself or MAY route the stanza to a specialized service that is stanza itself or route the stanza to a specialized service that is
responsible for that subdomain (if any). responsible for that subdomain (if the subdomain is configured), or
return an error to the sender (if the subdomain is not configured).
13.4 Bare Domain or Specific Resource 14.4 Mere Domain or Specific Resource
If the hostname of the domain identifier portion of the JID contained If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute matches the hostname of the server itself and in the 'to' attribute matches a configured hostname of the server
the JID contained in the 'to' attribute is of the form <domain> or itself and the JID contained in the 'to' attribute is of the form
<domain/resource>, the server (or a defined resource thereof) SHOULD <domain> or <domain/resource>, the server (or a defined resource
process the stanza as appropriate for the stanza kind. If the stanza thereof) MUST either process the stanza as appropriate for the stanza
is an IQ stanza and the server understands the namespace that kind or return an error stanza to the sender.
qualifies the content of the stanza, the server MUST either process
the request according to the semantics of the qualifying namespace or
reply with an IQ of type "error".
13.5 Node in Same Domain 14.5 Node in Same Domain
If the hostname of the domain identifier portion of the JID contained If the hostname of the domain identifier portion of the JID contained
in the 'to' attribute matches the hostname of the server itself and in the 'to' attribute matches a configured hostname of the server
the JID contained in the 'to' attribute is of the form <node@domain> itself and the JID contained in the 'to' attribute is of the form
or <node@domain/resource>, the server SHOULD deliver the stanza to <node@domain> or <node@domain/resource>, the server SHOULD deliver
the intended recipient of the stanza as represented by the JID the stanza to the intended recipient of the stanza as represented by
contained in the 'to' attribute. The following rules apply: the JID contained in the 'to' attribute. The following rules apply:
1. If the JID contains a resource identifier (i.e., is of the form 1. If the JID contains a resource identifier (i.e., is of the form
<node@domain/resource>) and there is an available resource whose <node@domain/resource>) and there is an available resource that
authzid matches the full JID, the recipient's server SHOULD matches the full JID, the recipient's server SHOULD deliver the
deliver the stanza to the session that exactly matches the stanza to the stream or session that exactly matches the resource
resource identifier. identifier.
2. If the JID contains a resource identifier and there is no 2. If the JID contains a resource identifier and there is no
available resource whose authzid matches the full JID, the available resource that matches the full JID, the recipient's
recipient's server SHOULD return to the sender a server SHOULD return to the sender a <service-unavailable/>
<recipient-unavailable/> stanza error. stanza error.
3. If the JID is of the form <node@domain> and there is at least one 3. If the JID is of the form <node@domain> and there is at least one
available resource available for the node, the recipient's server available resource available for the node, the recipient's server
MUST deliver the stanza to at least one of the available MUST deliver the stanza to at least one of the available
resources, according to application-specific rules (a set of resources, according to application-specific rules (a set of
delivery rules for instant messaging and presence applications is delivery rules for instant messaging and presence applications is
defined in XMPP IM [20]). defined in XMPP IM [21]).
14. Compliance Requirements 15. Compliance Requirements
This section summarizes the specific aspects of the Extensible This section summarizes the specific aspects of the Extensible
Messaging and Presence Protocol that MUST be supported by servers and Messaging and Presence Protocol that MUST be supported by servers and
clients in order to be considered compliant implementations, as well clients in order to be considered compliant implementations, as well
as additional protocol aspects that SHOULD be supported. For as additional protocol aspects that SHOULD be supported. For
compliance purposes, we draw a distinction between core protocols compliance purposes, we draw a distinction between core protocols
(which MUST be supported by any server or client, regardless of the (which MUST be supported by any server or client, regardless of the
specific application) and instant messaging protocols (which MUST be specific application) and instant messaging protocols (which MUST be
supported only by instant messaging and presence applications built supported only by instant messaging and presence applications built
on top of the core protocols). Compliance requirements that apply to on top of the core protocols). Compliance requirements that apply to
all servers and clients are specified in this section; compliance all servers and clients are specified in this section; compliance
requirements for instant messaging servers and clients are specified requirements for instant messaging servers and clients are specified
in the corresponding section of XMPP IM [20]. in the corresponding section of XMPP IM [21].
14.1 Servers 15.1 Servers
A server MUST support the following core protocols in order to be In addition to all defined requirements with regard to security, XML
considered compliant: usage, and internationalization, a server MUST support the following
core protocols in order to be considered compliant:
o Enforcement of the Nodeprep (Appendix A) and Resourceprep o Enforcement of the Nameprep [6], Nodeprep (Appendix A), and
(Appendix B) profiles of stringprep Resourceprep (Appendix B) profiles of stringprep
o XML streams (Section 4) as defined in this document, including o XML streams (Section 4), including stream encryption (Section 5)
stream encryption (Section 5) using TLS and stream authentication using TLS, stream authentication (Section 6) using SASL, and
(Section 6) using SASL resource binding (Section 7)
o The basic semantics of the three defined XML stanzas (Section 8) o The basic semantics of the three defined stanza kinds (i.e.,
(i.e., <message/>, <presence/>, and <iq/>) <message/>, <presence/>, and <iq/>) as specified in stanza
semantics (Section 9.2)
o Generation (and, where appropriate, handling) of error syntax and o Generation (and, where appropriate, handling) of error syntax and
semantics related to streams, TLS, SASL, and XML stanzas semantics related to streams, TLS, SASL, and XML stanzas
In addition, a server SHOULD support the following core protocol: In addition, a server SHOULD support the following core protocol:
o Server dialback (Section 7) o Server dialback (Section 8)
14.2 Clients 15.2 Clients
A client MUST support the following core protocols in order to be A client MUST support the following core protocols in order to be
considered compliant: considered compliant:
o XML streams (Section 4) as defined in this document, including o XML streams (Section 4), including stream encryption (Section 5)
stream encryption (Section 5) using TLS and stream authentication using TLS, stream authentication (Section 6) using SASL, and
(Section 6) using SASL resource binding (Section 7)
o The basic semantics of the three defined XML stanzas (Section 8) o The basic semantics of the three defined stanza kinds (i.e.,
(i.e., <message/>, <presence/>, and <iq/>) <message/>, <presence/>, and <iq/>) as specified in stanza
semantics (Section 9.2)
o Handling (and, where appropriate, generation) of error syntax and o Handling (and, where appropriate, generation) of error syntax and
semantics related to streams, TLS, SASL, and XML stanzas semantics related to streams, TLS, SASL, and XML stanzas
In addition, a client SHOULD support the following core protocols: In addition, a client SHOULD support the following core protocols:
o Generation of addresses in accordance with the Nodeprep (Appendix o Generation of addresses in accordance with the Nameprep [6],
A) and Resourceprep (Appendix B) profiles of stringprep Nodeprep (Appendix A), and Resourceprep (Appendix B) profiles of
stringprep
Normative References Normative References
[1] World Wide Web Consortium, "Extensible Markup Language (XML) [1] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
1.0 (Second Edition)", W3C xml, October 2000, <http:// "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC-xml,
www.w3.org/TR/2000/REC-xml-20001006>. October 2000, <http://www.w3.org/TR/REC-xml>.
[2] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging / [2] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging /
Presence Protocol Requirements", RFC 2779, February 2000. Presence Protocol Requirements", RFC 2779, February 2000.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[4] University of Southern California, "Transmission Control [4] Postel, J., "Transmission Control Protocol", STD 7, RFC 793,
Protocol", RFC 793, September 1981, <http://www.ietf.org/rfc/ September 1981.
rfc0793.txt>.
[5] Internet Assigned Numbers Authority, "Internet Assigned Numbers [5] Internet Assigned Numbers Authority, "Internet Assigned Numbers
Authority", January 1998, <http://www.iana.org/>. Authority", January 1998, <http://www.iana.org/>.
[6] Harrenstien, K., Stahl, M. and E. Feinler, "DoD Internet host [6] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile
table specification", RFC 952, October 1985.
[7] Braden, R., "Requirements for Internet Hosts - Application and
Support", STD 3, RFC 1123, October 1989.
[8] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile
for Internationalized Domain Names (IDN)", RFC 3491, March for Internationalized Domain Names (IDN)", RFC 3491, March
2003. 2003.
[9] Hoffman, P. and M. Blanchet, "Preparation of Internationalized [7] Hoffman, P. and M. Blanchet, "Preparation of Internationalized
Strings ("stringprep")", RFC 3454, December 2002. Strings ("stringprep")", RFC 3454, December 2002.
[10] World Wide Web Consortium, "Namespaces in XML", W3C xml-names, [8] Crocker, D. and P. Overell, "Augmented BNF for Syntax
January 1999, <http://www.w3.org/TR/1999/ Specifications: ABNF", RFC 2234, November 1997.
REC-xml-names-19990114/>.
[9] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.
[10] Bray, T., Hollander, D. and A. Layman, "Namespaces in XML", W3C
REC-xml-names, January 1999, <http://www.w3.org/TR/
REC-xml-names>.
[11] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and [11] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and
P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January
1999. 1999.
[12] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [12] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[13] Myers, J., "Simple Authentication and Security Layer (SASL)", [13] Myers, J., "Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997. RFC 2222, October 1997.
[14] Alvestrand, H., "IETF Policy on Character Sets and Languages", [14] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
RFC 3548, July 2003.
[15] Alvestrand, H., "IETF Policy on Character Sets and Languages",
BCP 18, RFC 2277, January 1998. BCP 18, RFC 2277, January 1998.
[15] Alvestrand, H., "Tags for the Identification of Languages", BCP [16] Alvestrand, H., "Tags for the Identification of Languages", BCP
47, RFC 3066, January 2001. 47, RFC 3066, January 2001.
[16] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC [17] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998. 2279, January 1998.
[17] International Organization for Standardization, "Information [18] International Organization for Standardization, "Information
Technology - Universal Multiple-octet coded Character Set (UCS) Technology - Universal Multiple-octet coded Character Set (UCS)
- Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO - Amendment 2: UCS Transformation Format 8 (UTF-8)", ISO
Standard 10646-1 Addendum 2, October 1996. Standard 10646-1 Addendum 2, October 1996.
[18] Linn, J., "Generic Security Service Application Program [19] Linn, J., "Generic Security Service Application Program
Interface, Version 2", RFC 2078, January 1997. Interface, Version 2", RFC 2078, January 1997.
[19] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for [20] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782, specifying the location of services (DNS SRV)", RFC 2782,
February 2000. February 2000.
Informative References Informative References
[20] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging", [21] Saint-Andre, P. and J. Miller, "XMPP Instant Messaging",
draft-ietf-xmpp-im-17 (work in progress), September 2003. draft-ietf-xmpp-im-18 (work in progress), October 2003.
[21] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., [22] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999. HTTP/1.1", RFC 2616, June 1999.
[22] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [23] 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.
[23] Mealling, M., "The IANA XML Registry", [24] Mealling, M., "The IETF XML Registry",
draft-mealling-iana-xmlns-registry-05 (work in progress), June draft-mealling-iana-xmlns-registry-05 (work in progress), June
2003. 2003.
[24] Crispin, M., "Internet Message Access Protocol - Version [25] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 2060, December 1996. 4rev1", RFC 2060, December 1996.
[25] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD [26] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD
53, RFC 1939, May 1996. 53, RFC 1939, May 1996.
[26] Newman, C. and J. Myers, "ACAP -- Application Configuration [27] Newman, C. and J. Myers, "ACAP -- Application Configuration
Access Protocol", RFC 2244, November 1997. Access Protocol", RFC 2244, November 1997.
[27] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595, [28] Newman, C., "Using TLS with IMAP, POP3 and ACAP", RFC 2595,
June 1999. June 1999.
[28] Eastlake, D., "Domain Name System Security Extensions", RFC [29] Eastlake, D., "Domain Name System Security Extensions", RFC
2535, March 1999. 2535, March 1999.
[29] Jabber Software Foundation, "Jabber Software Foundation", [30] Jabber Software Foundation, "Jabber Software Foundation",
<http://www.jabber.org/>. <http://www.jabber.org/>.
Authors' Addresses Authors' Addresses
Peter Saint-Andre Peter Saint-Andre
Jabber Software Foundation Jabber Software Foundation
EMail: stpeter@jabber.org EMail: stpeter@jabber.org
Jeremie Miller Jeremie Miller
Jabber Software Foundation Jabber Software Foundation
EMail: jeremie@jabber.org EMail: jeremie@jabber.org
Appendix A. Nodeprep Appendix A. Nodeprep
A.1 Introduction A.1 Introduction
This appendix defines the "Nodeprep" profile of stringprep (RFC 3454 This appendix defines the "Nodeprep" profile of stringprep (RFC 3454
[9]). As such, it specifies processing rules that will enable users [7]). As such, it specifies processing rules that will enable users
to enter internationalized node identifiers in XMPP and have the to enter internationalized node identifiers in the Extensible
highest chance of getting the content of the strings correct. These Messaging and Presence Protocol (XMPP) and have the highest chance of
processing rules are intended only for XMPP node identifiers (which getting the content of the strings correct. (An XMPP node identifier
are often associated with usernames), and are not intended for is the optional portion of an XMPP address that precedes a domain
arbitrary text. identifier and the '@' separator; it is often but not exclusively
associated with an instant messaging username.) These processing
rules are intended only for XMPP node identifiers and are not
intended for arbitrary text or any other aspect of an XMPP address.
This profile defines the following, as required by RFC 3454 [9]: This profile defines the following, as required by RFC 3454 [7]:
o The intended applicability of the profile: internationalized node o The intended applicability of the profile: internationalized node
identifiers within XMPP identifiers within XMPP
o The character repertoire that is the input and output to o The character repertoire that is the input and output to
stringprep: Unicode 3.2, specified in section 2 of this Appendix stringprep: Unicode 3.2, specified in Section 2 of this Appendix
o The mappings used: specified in section 3 o The mappings used: specified in Section 3
o The Unicode normalization used: specified in section 4 o The Unicode normalization used: specified in Section 4
o The characters that are prohibited as output: specified in section o The characters that are prohibited as output: specified in Section
5 5
o Bidirectional character handling: specified in section 6 o Bidirectional character handling: specified in Section 6
A.2 Character Repertoire A.2 Character Repertoire
This profile uses Unicode 3.2 with the list of unassigned code points This profile uses Unicode 3.2 with the list of unassigned code points
being Table A.1, both defined in Appendix A of RFC 3454 [9]. being Table A.1, both defined in Appendix A of RFC 3454 [7].
A.3 Mapping A.3 Mapping
This profile specifies mapping using the following tables from RFC This profile specifies mapping using the following tables from RFC
3454 [9]: 3454 [7]:
Table B.1 Table B.1
Table B.2 Table B.2
A.4 Normalization A.4 Normalization
This profile specifies using Unicode normalization form KC, as This profile specifies using Unicode normalization form KC, as
described in RFC 3454 [9]. described in RFC 3454 [7].
A.5 Prohibited Output A.5 Prohibited Output
This profile specifies prohibiting use of the following tables from This profile specifies prohibiting use of the following tables from
RFC 3454 [9]. RFC 3454 [7].
Table C.1.1 Table C.1.1
Table C.1.2 Table C.1.2
Table C.2.1 Table C.2.1
Table C.2.2 Table C.2.2
Table C.3 Table C.3
skipping to change at page 75, line 8 skipping to change at page 74, line 48
#x3C (<) #x3C (<)
#x3E (>) #x3E (>)
#x40 (@) #x40 (@)
A.6 Bidirectional Characters A.6 Bidirectional Characters
This profile specifies checking bidirectional strings as described in This profile specifies checking bidirectional strings as described in
section 6 of RFC 3454 [9]. Section 6 of RFC 3454 [7].
Appendix B. Resourceprep Appendix B. Resourceprep
B.1 Introduction B.1 Introduction
This appendix defines the "Resourceprep" profile of stringprep (RFC This appendix defines the "Resourceprep" profile of stringprep (RFC
3454 [9]). As such, it specifies processing rules that will enable 3454 [7]). As such, it specifies processing rules that will enable
users to enter internationalized resource identifiers in XMPP and users to enter internationalized resource identifiers in the
have the highest chance of getting the content of the strings Extensible Messaging and Presence Protocol (XMPP) and have the
correct. These processing rules are intended only for XMPP resource highest chance of getting the content of the strings correct. (An
identifiers (which are often associated with session names), and are XMPP resource identifier is the optional portion of an XMPP address
not intended for arbitrary text. that follows a domain identifier and the '/' separator; it is often
but not exclusively associated with an instant messaging session
name.) These processing rules are intended only for XMPP resource
identifiers and are not intended for arbitrary text or any other
aspect of an XMPP address.
This profile defines the following, as required by RFC 3454 [9]: This profile defines the following, as required by RFC 3454 [7]:
o The intended applicability of the profile: internationalized o The intended applicability of the profile: internationalized
resource identifiers within XMPP resource identifiers within XMPP
o The character repertoire that is the input and output to o The character repertoire that is the input and output to
stringprep: Unicode 3.2, specified in section 2 of this Appendix stringprep: Unicode 3.2, specified in Section 2 of this Appendix
o The mappings used: specified in section 3 o The mappings used: specified in Section 3
o The Unicode normalization used: specified in section 4 o The Unicode normalization used: specified in Section 4
o The characters that are prohibited as output: specified in section o The characters that are prohibited as output: specified in Section
5 5
o Bidirectional character handling: specified in section 6 o Bidirectional character handling: specified in Section 6
B.2 Character Repertoire B.2 Character Repertoire
This profile uses Unicode 3.2 with the list of unassigned code points This profile uses Unicode 3.2 with the list of unassigned code points
being Table A.1, both defined in Appendix A of RFC 3454 [9]. being Table A.1, both defined in Appendix A of RFC 3454 [7].
B.3 Mapping B.3 Mapping
This profile specifies mapping using the following tables from RFC This profile specifies mapping using the following tables from RFC
3454 [9]: 3454 [7]:
Table B.1 Table B.1
B.4 Normalization B.4 Normalization
This profile specifies using Unicode normalization form KC, as This profile specifies using Unicode normalization form KC, as
described in RFC 3454 [9]. described in RFC 3454 [7].
B.5 Prohibited Output B.5 Prohibited Output
This profile specifies prohibiting use of the following tables from This profile specifies prohibiting use of the following tables from
RFC 3454 [9]. RFC 3454 [7].
Table C.1.2 Table C.1.2
Table C.2.1 Table C.2.1
Table C.2.2 Table C.2.2
Table C.3 Table C.3
Table C.4 Table C.4
skipping to change at page 77, line 33 skipping to change at page 76, line 34
Table C.7 Table C.7
Table C.8 Table C.8
Table C.9 Table C.9
B.6 Bidirectional Characters B.6 Bidirectional Characters
This profile specifies checking bidirectional strings as described in This profile specifies checking bidirectional strings as described in
section 6 of RFC 3454 [9]. Section 6 of RFC 3454 [7].
Appendix C. XML Schemas Appendix C. XML Schemas
The following XML schemas are descriptive, not normative. For schemas The following XML schemas are descriptive, not normative. For schemas
defining the 'jabber:client' and 'jabber:server' namespaces, refer to defining the 'jabber:client' and 'jabber:server' namespaces, refer to
XMPP IM [20]. XMPP IM [21].
C.1 Stream namespace C.1 Streams namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='http://etherx.jabber.org/streams' targetNamespace='http://etherx.jabber.org/streams'
xmlns='http://etherx.jabber.org/streams' xmlns='http://etherx.jabber.org/streams'
elementFormDefault='unqualified'> elementFormDefault='unqualified'>
<xs:import namespace='http://www.w3.org/XML/1998/namespace'
schemaLocation='http://www.w3.org/2001/xml.xsd'/>
<xs:element name='stream'> <xs:element name='stream'>
<xs:complexType> <xs:complexType>
<xs:sequence> <xs:sequence>
<xs:element ref='features' minOccurs='0' maxOccurs='1'/> <xs:element ref='features' minOccurs='0' maxOccurs='1'/>
<xs:choice minOccurs='0' maxOccurs='1'> <xs:choice minOccurs='0' maxOccurs='1'>
<xs:any namespace='jabber:client' <xs:any namespace='jabber:client'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
<xs:any namespace='jabber:server' <xs:any namespace='jabber:server'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:choice> </xs:choice>
<xs:element ref='error' minOccurs='0' maxOccurs='1'/> <xs:element ref='error' minOccurs='0' maxOccurs='1'/>
</xs:sequence> </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:NMTOKEN' use='optional'/> <xs:attribute name='id' type='xs:NMTOKEN' use='optional'/>
<xs:attribute ref='xml:lang' 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:sequence> <xs:sequence>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
skipping to change at page 79, line 4 skipping to change at page 77, line 39
<xs:element name='features'> <xs:element name='features'>
<xs:complexType> <xs:complexType>
<xs:sequence> <xs:sequence>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='unbounded'/> maxOccurs='unbounded'/>
</xs:sequence> </xs:sequence>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='error'> <xs:element name='error'>
<xs:complexType> <xs:complexType>
<xs:sequence> <xs:sequence>
<xs:any namespace='urn:ietf:params:xml:ns:xmpp-streams' <xs:any namespace='urn:ietf:params:xml:ns:xmpp-streams'
maxOccurs='1'/> maxOccurs='2'/>
<xs:any <xs:any
namespace='##other' namespace='##other'
minOccurs='0' minOccurs='0'
maxOccurs='1'/> maxOccurs='1'/>
</xs:sequence> </xs:sequence>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
</xs:schema> </xs:schema>
C.2 Stream error namespace C.2 Stream error namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
xmlns:xml='http://www.w3.org/XML/1998/namespace' xmlns:xml='http://www.w3.org/XML/1998/namespace'
targetNamespace='urn:ietf:params:xml:ns:xmpp-streams' targetNamespace='urn:ietf:params:xml:ns:xmpp-streams'
skipping to change at page 79, line 41 skipping to change at page 78, line 28
schemaLocation='http://www.w3.org/2001/xml.xsd'/> schemaLocation='http://www.w3.org/2001/xml.xsd'/>
<xs:element name='bad-format' type='empty'/> <xs:element name='bad-format' type='empty'/>
<xs:element name='bad-namespace-prefix' type='empty'/> <xs:element name='bad-namespace-prefix' type='empty'/>
<xs:element name='conflict' type='empty'/> <xs:element name='conflict' type='empty'/>
<xs:element name='connection-timeout' type='empty'/> <xs:element name='connection-timeout' type='empty'/>
<xs:element name='host-gone' type='empty'/> <xs:element name='host-gone' type='empty'/>
<xs:element name='host-unknown' type='empty'/> <xs:element name='host-unknown' type='empty'/>
<xs:element name='improper-addressing' type='empty'/> <xs:element name='improper-addressing' type='empty'/>
<xs:element name='internal-server-error' type='empty'/> <xs:element name='internal-server-error' type='empty'/>
<xs:element name='invalid-from' type='empty'/>
<xs:element name='invalid-id' type='empty'/> <xs:element name='invalid-id' type='empty'/>
<xs:element name='invalid-namespace' type='empty'/> <xs:element name='invalid-namespace' type='empty'/>
<xs:element name='invalid-xml' type='empty'/> <xs:element name='invalid-xml' type='empty'/>
<xs:element name='nonmatching-hosts' type='empty'/>
<xs:element name='not-authorized' type='empty'/> <xs:element name='not-authorized' type='empty'/>
<xs:element name='policy-violation' type='empty'/> <xs:element name='policy-violation' type='empty'/>
<xs:element name='remote-connection-failed' type='empty'/> <xs:element name='remote-connection-failed' type='empty'/>
<xs:element name='resource-constraint' type='empty'/> <xs:element name='resource-constraint' type='empty'/>
<xs:element name='restricted-xml' type='empty'/> <xs:element name='restricted-xml' type='empty'/>
<xs:element name='see-other-host' type='empty'/> <xs:element name='see-other-host' type='xs:string'/>
<xs:element name='system-shutdown' type='empty'/> <xs:element name='system-shutdown' type='empty'/>
<xs:element name='undefined-condition' type='empty'/> <xs:element name='undefined-condition' type='empty'/>
<xs:element name='unsupported-encoding' type='empty'/> <xs:element name='unsupported-encoding' type='empty'/>
<xs:element name='unsupported-stanza-type' type='empty'/> <xs:element name='unsupported-stanza-type' type='empty'/>
<xs:element name='unsupported-version' type='empty'/> <xs:element name='unsupported-version' type='empty'/>
<xs:element name='xml-not-well-formed' type='empty'/> <xs:element name='xml-not-well-formed' type='empty'/>
<xs:element name='text' type='xs:string'> <xs:element name='text' type='xs:string'>
<xs:complexType> <xs:complexType>
<xs:attribute ref='xml:lang' use='optional'/> <xs:attribute ref='xml:lang' use='optional'/>
skipping to change at page 81, line 48 skipping to change at page 80, line 36
<xs:element name='challenge' type='xs:NMTOKEN'/> <xs:element name='challenge' type='xs:NMTOKEN'/>
<xs:element name='response' type='xs:NMTOKEN'/> <xs:element name='response' type='xs:NMTOKEN'/>
<xs:element name='abort' type='empty'/> <xs:element name='abort' type='empty'/>
<xs:element name='success' type='empty'/> <xs:element name='success' type='empty'/>
<xs:element name='failure'> <xs:element name='failure'>
<xs:complexType> <xs:complexType>
<xs:choice maxOccurs='1'> <xs:choice maxOccurs='1'>
<xs:element ref='aborted'/> <xs:element ref='aborted'/>
<xs:element ref='bad-protocol'/> <xs:element ref='incorrect-encoding'/>
<xs:element ref='encryption-required'/>
<xs:element ref='invalid-authzid'/> <xs:element ref='invalid-authzid'/>
<xs:element ref='invalid-mechanism'/> <xs:element ref='invalid-mechanism'/>
<xs:element ref='invalid-realm'/>
<xs:element ref='mechanism-too-weak'/> <xs:element ref='mechanism-too-weak'/>
<xs:element ref='not-authorized'/> <xs:element ref='not-authorized'/>
<xs:element ref='temporary-auth-failure'/> <xs:element ref='temporary-auth-failure'/>
</xs:choice> </xs:choice>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
<xs:element name='aborted' type='empty'/> <xs:element name='aborted' type='empty'/>
<xs:element name='bad-protocol' type='empty'/> <xs:element name='incorrect-encoding' type='empty'/>
<xs:element name='encryption-required' type='empty'/>
<xs:element name='invalid-authzid' type='empty'/> <xs:element name='invalid-authzid' type='empty'/>
<xs:element name='invalid-mechanism' type='empty'/> <xs:element name='invalid-mechanism' type='empty'/>
<xs:element name='invalid-realm' type='empty'/>
<xs:element name='mechanism-too-weak' type='empty'/> <xs:element name='mechanism-too-weak' type='empty'/>
<xs:element name='not-authorized' type='empty'/> <xs:element name='not-authorized' type='empty'/>
<xs:element name='temporary-auth-failure' type='empty'/> <xs:element name='temporary-auth-failure' type='empty'/>
<xs:simpleType name='empty'> <xs:simpleType name='empty'>
<xs:restriction base='xs:string'> <xs:restriction base='xs:string'>
<xs:enumeration value=''/> <xs:enumeration value=''/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:schema> </xs:schema>
C.5 Dialback namespace C.5 Resource binding namespace
<?xml version='1.0' encoding='UTF-8'?>
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='urn:ietf:params:xml:ns:xmpp-bind'
xmlns='urn:ietf:params:xml:ns:xmpp-bind'
elementFormDefault='qualified'>
<xs:element name='bind'>
<xs:complexType>
<xs:choice minOccurs='0' maxOccurs='1'>
<xs:element ref='resource'/>
<xs:element ref='jid'/>
</xs:choice>
</xs:complexType>
</xs:element>
<xs:element name='resource' type='xs:string'/>
<xs:element name='jid' type='xs:string'/>
</xs:schema>
C.6 Dialback namespace
<?xml version='1.0' encoding='UTF-8'?> <?xml version='1.0' encoding='UTF-8'?>
<xs:schema <xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='jabber:server:dialback' targetNamespace='jabber:server:dialback'
xmlns='jabber:server:dialback' xmlns='jabber:server:dialback'
elementFormDefault='qualified'> elementFormDefault='qualified'>
<xs:element name='result'> <xs:element name='result'>
skipping to change at page 83, line 35 skipping to change at page 82, line 42
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:attribute> </xs:attribute>
</xs:extension> </xs:extension>
</xs:simpleContent> </xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
</xs:schema> </xs:schema>
C.6 Stanza error namespace C.7 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'
xmlns:xml='http://www.w3.org/XML/1998/namespace' xmlns:xml='http://www.w3.org/XML/1998/namespace'
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:import namespace='http://www.w3.org/XML/1998/namespace' <xs:import namespace='http://www.w3.org/XML/1998/namespace'
schemaLocation='http://www.w3.org/2001/xml.xsd'/> schemaLocation='http://www.w3.org/2001/xml.xsd'/>
<xs:element name='bad-request' type='empty'/> <xs:element name='bad-request' type='empty'/>
<xs:element name='conflict' type='empty'/> <xs:element name='conflict' type='empty'/>
<xs:element name='feature-not-implemented' type='empty'/> <xs:element name='feature-not-implemented' type='empty'/>
<xs:element name='forbidden' type='empty'/> <xs:element name='forbidden' type='empty'/>
<xs:element name='gone' type='xs:string'/>
<xs:element name='internal-server-error' type='empty'/> <xs:element name='internal-server-error' type='empty'/>
<xs:element name='item-not-found' type='empty'/> <xs:element name='item-not-found' type='empty'/>
<xs:element name='jid-malformed' type='empty'/> <xs:element name='jid-malformed' type='empty'/>
<xs:element name='not-acceptable' type='empty'/>
<xs:element name='not-allowed' type='empty'/> <xs:element name='not-allowed' type='empty'/>
<xs:element name='payment-required' type='empty'/> <xs:element name='payment-required' type='empty'/>
<xs:element name='recipient-unavailable' type='empty'/> <xs:element name='recipient-unavailable' type='empty'/>
<xs:element name='redirect' type='xs:string'/>
<xs:element name='registration-required' type='empty'/> <xs:element name='registration-required' type='empty'/>
<xs:element name='remote-server-not-found' type='empty'/> <xs:element name='remote-server-not-found' type='empty'/>
<xs:element name='remote-server-timeout' type='empty'/> <xs:element name='remote-server-timeout' type='empty'/>
<xs:element name='resource-constraint' type='empty'/> <xs:element name='resource-constraint' type='empty'/>
<xs:element name='service-unavailable' type='empty'/> <xs:element name='service-unavailable' type='empty'/>
<xs:element name='subscription-required' type='empty'/> <xs:element name='subscription-required' type='empty'/>
<xs:element name='undefined-condition' type='empty'/> <xs:element name='undefined-condition' type='empty'/>
<xs:element name='unexpected-request' type='empty'/> <xs:element name='unexpected-request' type='empty'/>
<xs:element name='text' type='xs:string'> <xs:element name='text' type='xs:string'>
skipping to change at page 85, line 5 skipping to change at page 83, line 45
</xs:element> </xs:element>
<xs:simpleType name='empty'> <xs:simpleType name='empty'>
<xs:restriction base='xs:string'> <xs:restriction base='xs:string'>
<xs:enumeration value=''/> <xs:enumeration value=''/>
</xs:restriction> </xs:restriction>
</xs:simpleType> </xs:simpleType>
</xs:schema> </xs:schema>
Appendix D. Differences Between Jabber and XMPP Appendix D. Differences Between Core Jabber Protocol and XMPP
This section is non-normative. This section is non-normative.
XMPP has been adapted from the protocols originally developed in the XMPP has been adapted from the protocols originally developed in the
Jabber open-source community, which can be thought of as "XMPP 0.9". Jabber open-source community, which can be thought of as "XMPP 0.9".
Because there exists a large installed base of Jabber implementations Because there exists a large installed base of Jabber implementations
and deployments, it may be helpful to specify the key differences and deployments, it may be helpful to specify the key differences
between Jabber and XMPP in order to expedite and encourage upgrades between Jabber and XMPP in order to expedite and encourage upgrades
of those implementations and deployments to XMPP. This section of those implementations and deployments to XMPP. This section
summarizes the core differences, and the corresponding section of summarizes the core differences, while the corresponding section of
XMPP IM [20] summarizes the differences that relate specifically to XMPP IM [21] summarizes the differences that relate specifically to
instant messaging and presence applications. instant messaging and presence applications.
D.1 Authentication D.1 Channel Encryption
It is common practice in the Jabber community to use SSL for channel
encryption on ports other than 5222 and 5269 (the convention is to
use ports 5223 and 5270). XMPP uses TLS over the IANA-registered
ports for channel encryption, as defined under Stream Encryption
(Section 5) herein.
D.2 Authentication
The client-server authentication protocol developed in the Jabber The client-server authentication protocol developed in the Jabber
community uses a basic IQ interaction qualified by the community uses a basic IQ interaction qualified by the
'jabber:iq:auth' namespace (documentation of this protocol is 'jabber:iq:auth' namespace (documentation of this protocol is
contained in "JEP-0078: Non-SASL Authentication", published by the contained in "JEP-0078: Non-SASL Authentication", published by the
Jabber Software Foundation [29]). XMPP uses SASL for authentication, Jabber Software Foundation [30]). XMPP uses SASL for authentication,
as defined in the Stream Authentication (Section 6) section of this as defined under Stream Authentication (Section 6) herein.
document.
The Jabber community does not currently possess an authentication The Jabber community does not currently possess an authentication
protocol for server-to-server communications, only the Server protocol for server-to-server communications, only the Server
Dialback (Section 7) protocol to prevent server spoofing. XMPP Dialback (Section 8) protocol to prevent server spoofing. XMPP
augments Server Dialback with a true server-to-server authentication augments Server Dialback with a true server-to-server authentication
protocol, as defined in the Stream Authentication (Section 6) section protocol, as defined under Stream Authentication (Section 6) herein.
of this document.
D.2 Channel Encryption D.3 Resource Binding
It is common practice in the Jabber community to use SSL for channel Resource binding in the Jabber community is handled via the
encryption on ports other than 5222 and 5269 (the convention is to 'jabber:iq:auth' namespace that is also used for client
use ports 5223 and 5270). XMPP uses TLS over the IANA-registered authentication with a server. XMPP defines a dedicated namespace for
ports for channel encryption, as defined in the Stream Encryption resource binding as well as the ability for a server to generate a
(Section 5) section of this document. resource identifier on behalf of a client, as defined under Resource
Binding (Section 7).
D.3 JID Processing D.4 JID Processing
JID processing was somewhat loosely defined by the Jabber community JID processing was somewhat loosely defined by the Jabber community
(documentation of forbidden characters and case handling is contained (documentation of forbidden characters and case handling is contained
in "JEP-0029: Definition of Jabber Identifiers", published by the in "JEP-0029: Definition of Jabber Identifiers", published by the
Jabber Software Foundation [29]). XMPP defines two stringprep [9] Jabber Software Foundation [30]). XMPP specifies the use of Nameprep
profiles for JID processing: Nodeprep (Appendix A) and Resourceprep [6] for domain identifiers and supplements Nameprep with two
(Appendix B). additional stringprep [7] profiles for JID processing: Nodeprep
(Appendix A) for node identifiers and Resourceprep (Appendix B) for
resource identifiers .
D.4 Error Handling D.5 Error Handling
Stream-related errors are handled in the Jabber community via simple Stream-related errors are handled in the Jabber community via simple
CDATA text in a <stream:error/> element. In XMPP, stream-related CDATA text in a <stream:error/> element. In XMPP, stream-related
errors are handled via an extensible mechanism defined in the Stream errors are handled via an extensible mechanism defined under Stream
Errors (Section 4.6) section of this document. Errors (Section 4.6) herein.
Stanza-related errors are handled in the Jabber community via Stanza-related errors are handled in the Jabber community via
HTTP-style error codes. In XMPP, stanza-related errors are handled HTTP-style error codes. In XMPP, stanza-related errors are handled
via an extensible mechanism defined in the Stanza Errors (Section via an extensible mechanism defined under Stanza Errors (Section 9.3)
8.3) section of this document. (Documentation of a mapping between herein. (Documentation of a mapping between Jabber and XMPP error
Jabber and XMPP error handling mechanisms is contained in "JEP-0086: handling mechanisms is contained in "JEP-0086: Legacy Errors",
Legacy Errors", published by the Jabber Software Foundation [29].) published by the Jabber Software Foundation [30].)
D.5 Internationalization D.6 Internationalization
Although use of UTF-8 has always been standard practice within the Although use of UTF-8 has always been standard practice within the
Jabber community, the community did not define mechanisms for Jabber community, the community did not define mechanisms for
specifying the language of human-readable text provided in CDATA specifying the language of human-readable text provided in CDATA
sections. XMPP specifies the use of the 'xml:lang' attribute in such sections. XMPP specifies the use of the 'xml:lang' attribute in such
contexts, as defined in the xml:lang (Section 8.1.5) section of this contexts, as defined under Stream Attributes (Section 4.2) and
document. xml:lang (Section 9.1.5) herein.
D.6 Stream Version Attribute D.7 Stream Version Attribute
The Jabber community does not include a 'version' attribute in stream The Jabber community does not include a 'version' attribute in stream
headers. XMPP specifies inclusion of that attribute, with a value of headers. XMPP specifies inclusion of that attribute, with a value of
'1.0', as a way to signal support for the stream features '1.0', as a way to signal support for the stream features
(authentication, encryption, etc.) defined in the Version Support (authentication, encryption, etc.) defined under Version Support
(Section 4.2.1) section of this document. (Section 4.2.1) herein.
Appendix E. Revision History Appendix E. Revision History
Note to RFC Editor: please remove this entire appendix, and the Note to RFC Editor: please remove this entire appendix, and the
corresponding entries in the table of contents, prior to publication. corresponding entries in the table of contents, prior to publication.
E.1 Changes from draft-ietf-xmpp-core-17 E.1 Changes from draft-ietf-xmpp-core-18
o Added the 'xml:lang' attribute to the root <stream/> element per
previous consensus and list discussion.
o Added the <gone/>, <not-acceptable/>, and <redirect/> stanza
errors.
o Changed dataype of <see-other-host/> stream error and of <gone/>
and <redirect/> stanza errors to xs:string so that these elements
may contain programmatic information.
o Removed <invalid-realm/> and <bad-protocol/> SASL errors.
o Removed references to RFC 952 and RFC 1123 (domain name format is
handled by reference to Nameprep).
o Changed address record resolution text so that it is not specific
to IPv4.
o Clarified text in appendices regarding scope of Nodeprep and
Resourceprep.
o Removed requirement that receiving entity terminate the TCP
connection upon receiving an <abort/> element from or sending a
<failure/> element to the initiating entity during SASL
negotiation.
o Removed recommendation that TLS and SASL security layer should not
both be used simultaneously.
o Added subsection to Security Considerations regarding use of
base64 in SASL.
o Specified rules regarding inclusion of username in SASL
negotiation.
o Adjusted content related to SASL authorization identities, since
the previous text did not track RFC2222bis.
o Added section on resource binding to compensate for changes to
SASL authorization identity text.
o Specified ABNF for JIDs.
o Checked all references.
o Completed a thorough proofreading and consistency check of the
entire text.
E.2 Changes from draft-ietf-xmpp-core-17
o Specified that UTF-8 is the only allowable encoding. o Specified that UTF-8 is the only allowable encoding.
o Added stream errors for <bad-namespace-prefix/>, <invalid-xml/>, o Added stream errors for <bad-namespace-prefix/>, <invalid-xml/>,
and <restricted-xml/>, as well as a <bad-format/> error for and <restricted-xml/>, as well as a <bad-format/> error for
generic XML error conditions. generic XML error conditions.
o Folded Nodeprep and Resourceprep profiles into this document. o Folded Nodeprep and Resourceprep profiles into this document.
o Moved most delivery handling rules from XMPP IM to XMPP Core. o Moved most delivery handling rules from XMPP IM to XMPP Core.
o Moved detailed stanza syntax descriptions from XMPP Core to XMPP o Moved detailed stanza syntax descriptions from XMPP Core to XMPP
IM. IM.
o Moved stanza schemas from XMPP Core to XMPP IM. o Moved stanza schemas from XMPP Core to XMPP IM.
E.2 Changes from draft-ietf-xmpp-core-16 E.3 Changes from draft-ietf-xmpp-core-16
o Added <conflict/> and <unsupported-encoding/> stream errors. o Added <conflict/> and <unsupported-encoding/> stream errors.
o Changed the datatype for the <see-other-host/> and o Changed the datatype for the <see-other-host/> and
<unsupported-version/> stream errors from 'xs:string' to 'empty'. <unsupported-version/> stream errors from 'xs:string' to 'empty'.
o Further clarified server handling of the basic stanza kinds. o Further clarified server handling of the basic stanza kinds.
o Further clarified character encoding rules per list discussion. o Further clarified character encoding rules per list discussion.
skipping to change at page 88, line 5 skipping to change at page 87, line 37
o Added stream closure to SASL failure cases in order to mirror o Added stream closure to SASL failure cases in order to mirror
handling of TLS failures. handling of TLS failures.
o Added section on compliance requirements for server and client o Added section on compliance requirements for server and client
implementations. implementations.
o Added non-normative section on differences between Jabber usage o Added non-normative section on differences between Jabber usage
and XMPP specifications. and XMPP specifications.
E.3 Changes from draft-ietf-xmpp-core-15 E.4 Changes from draft-ietf-xmpp-core-15
o Added <connection-timeout/> and <policy-violation/> stream errors. o Added <connection-timeout/> and <policy-violation/> stream errors.
o Added <aborted/> SASL error and clarified <bad-protocol/> error. o Added <aborted/> SASL error and clarified <bad-protocol/> error.
o Made 'id' required for IQ stanzas. o Made 'id' required for IQ stanzas.
E.4 Changes from draft-ietf-xmpp-core-14 E.5 Changes from draft-ietf-xmpp-core-14
o Added SRV lookup for client-to-server communications. o Added SRV lookup for client-to-server communications.
o Changed server SRV record to conform to RFC 2782; specifically, o Changed server SRV record to conform to RFC 2782; specifically,
the service identifier was changed from 'jabber' to the service identifier was changed from 'jabber' to
'jabber-server'. 'jabber-server'.
E.5 Changes from draft-ietf-xmpp-core-13 E.6 Changes from draft-ietf-xmpp-core-13
o Clarified stream restart after successful TLS and SASL o Clarified stream restart after successful TLS and SASL
negotiation. negotiation.
o Clarified requirement for resolution of DNS hostnames. o Clarified requirement for resolution of DNS hostnames.
o Clarified text regarding namespaces. o Clarified text regarding namespaces.
o Clarified examples regarding empty <stream:features/> element. o Clarified examples regarding empty <stream:features/> element.
o Added several more SASL error conditions. o Added several more SASL error conditions.
o Changed <invalid-xml/> stream error to <improper-addressing/> and o Changed <invalid-xml/> stream error to <improper-addressing/> and
added to schema. added to schema.
o Made small editorial changes and fixed several schema errors. o Made small editorial changes and fixed several schema errors.
E.6 Changes from draft-ietf-xmpp-core-12 E.7 Changes from draft-ietf-xmpp-core-12
o Moved server dialback to a separate section; clarified its o Moved server dialback to a separate section; clarified its
security characteristics and its role in the protocol. security characteristics and its role in the protocol.
o Adjusted error handling syntax and semantics per list discussion. o Adjusted error handling syntax and semantics per list discussion.
o Further clarified length of node identifiers and total length of o Further clarified length of node identifiers and total length of
JIDs. JIDs.
o Documented message type='normal'. o Documented message type='normal'.
o Corrected several small errors in the TLS and SASL sections. o Corrected several small errors in the TLS and SASL sections.
o Corrected several errors in the schemas. o Corrected several errors in the schemas.
E.7 Changes from draft-ietf-xmpp-core-11 E.8 Changes from draft-ietf-xmpp-core-11
o Corrected several small errors in the TLS and SASL sections. o Corrected several small errors in the TLS and SASL sections.
o Made small editorial changes and fixed several schema errors. o Made small editorial changes and fixed several schema errors.
E.8 Changes from draft-ietf-xmpp-core-10 E.9 Changes from draft-ietf-xmpp-core-10
o Adjusted TLS content regarding certificate validation process. o Adjusted TLS content regarding certificate validation process.
o Specified that stanza error extensions for specific applications o Specified that stanza error extensions for specific applications
are to be properly namespaced children of the relevant descriptive are to be properly namespaced children of the relevant descriptive
element. element.
o Clarified rules for inclusion of the 'id' attribute. o Clarified rules for inclusion of the 'id' attribute.
o Specified that the 'xml:lang' attribute SHOULD be included (per o Specified that the 'xml:lang' attribute SHOULD be included (per
list discussion). list discussion).
o Made small editorial changes and fixed several schema errors. o Made small editorial changes and fixed several schema errors.
E.9 Changes from draft-ietf-xmpp-core-09 E.10 Changes from draft-ietf-xmpp-core-09
o Fixed several dialback error conditions. o Fixed several dialback error conditions.
o Cleaned up rules regarding TLS and certificate processing based on o Cleaned up rules regarding TLS and certificate processing based on
off-list feedback. off-list feedback.
o Changed <stream-condition/> and <stanza-condition/> elements to o Changed <stream-condition/> and <stanza-condition/> elements to
<condition/>. <condition/>.
o Added or modified several stream and stanza error conditions. o Added or modified several stream and stanza error conditions.
o Specified only one child allowed for IQ, or two if type="error". o Specified only one child allowed for IQ, or two if type="error".
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
E.10 Changes from draft-ietf-xmpp-core-08 E.11 Changes from draft-ietf-xmpp-core-08
o Incorporated list discussion regarding addressing, SASL, TLS, TCP, o Incorporated list discussion regarding addressing, SASL, TLS, TCP,
dialback, namespaces, extensibility, and the meaning of 'ignore' dialback, namespaces, extensibility, and the meaning of 'ignore'
for routers and recipients. for routers and recipients.
o Specified dialback error conditions. o Specified dialback error conditions.
o Made small editorial changes to address RFC Editor requirements. o Made small editorial changes to address RFC Editor requirements.
E.11 Changes from draft-ietf-xmpp-core-07 E.12 Changes from draft-ietf-xmpp-core-07
o Made several small editorial changes. o Made several small editorial changes.
E.12 Changes from draft-ietf-xmpp-core-06 E.13 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 [23]. to the format defined in The IETF XML Registry [24].
o Removed note to RFC Editor regarding provisional namespace names. o Removed note to RFC Editor regarding provisional namespace names.
E.13 Changes from draft-ietf-xmpp-core-05 E.14 Changes from draft-ietf-xmpp-core-05
o Added <invalid-namespace/> as a stream error condition. o Added <invalid-namespace/> as a stream error condition.
o Adjusted security considerations per discussion at IETF 56 and on o Adjusted security considerations per discussion at IETF 56 and on
list. list.
E.14 Changes from draft-ietf-xmpp-core-04 E.15 Changes from draft-ietf-xmpp-core-04
o Added server-to-server examples for TLS and SASL. o Added server-to-server examples for TLS and SASL.
o Changed error syntax, rules, and examples based on list o Changed error syntax, rules, and examples based on list
discussion. discussion.
o Added schemas for the TLS, stream error, and stanza error o Added schemas for the TLS, stream error, and stanza error
namespaces. namespaces.
o Added note to RFC Editor regarding provisional namespace names. o Added note to RFC Editor regarding provisional namespace names.
o Made numerous small editorial changes and clarified text o Made numerous small editorial changes and clarified text
throughout. throughout.
E.15 Changes from draft-ietf-xmpp-core-03 E.16 Changes from draft-ietf-xmpp-core-03
o Clarified rules and procedures for TLS and SASL. o Clarified rules and procedures for TLS and SASL.
o Amplified stream error code syntax per list discussion. o Amplified stream error code syntax per list discussion.
o Made numerous small editorial changes. o Made numerous small editorial changes.
E.16 Changes from draft-ietf-xmpp-core-02 E.17 Changes from draft-ietf-xmpp-core-02
o Added dialback schema. o Added dialback schema.
o Removed all DTDs since schemas provide more complete definitions. o Removed all DTDs since schemas provide more complete definitions.
o Added stream error codes. o Added stream error codes.
o Clarified error code "philosophy". o Clarified error code "philosophy".
E.17 Changes from draft-ietf-xmpp-core-01 E.18 Changes from draft-ietf-xmpp-core-01
o Updated the addressing restrictions per list discussion and added o Updated the addressing restrictions per list discussion and added
references to the new Nodeprep and Resourceprep profiles. references to the new Nodeprep and Resourceprep profiles.
o Corrected error in Stream Authentication regarding 'version' o Corrected error in Stream Authentication regarding 'version'
attribute. attribute.
o Made numerous small editorial changes. o Made numerous small editorial changes.
E.18 Changes from draft-ietf-xmpp-core-00 E.19 Changes from draft-ietf-xmpp-core-00
o Added information about TLS from list discussion. o Added information about TLS from list discussion.
o Clarified meaning of "ignore" based on list discussion. o Clarified meaning of "ignore" based on list discussion.
o Clarified information about Universal Character Set data and o Clarified information about Universal Character Set data and
character encodings. character encodings.
o Provided base64-decoded information for examples. o Provided base64-decoded information for examples.
o Fixed several errors in the schemas. o Fixed several errors in the schemas.
o Made numerous small editorial fixes. o Made numerous small editorial fixes.
E.19 Changes from draft-miller-xmpp-core-02 E.20 Changes from draft-miller-xmpp-core-02
o Brought Streams Authentication section into line with discussion o Brought Stream Authentication section into line with discussion on
on list and at IETF 55 meeting. 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".
 End of changes. 402 change blocks. 
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