JEP-0177: Jingle Raw UDP Transport

Joe Beda

Email: jbeda@google.com
JID: jbeda@google.com

Peter Saint-Andre

Email: stpeter@jabber.org
JID: stpeter@jabber.org

Scott Ludwig

Email: scottlu@google.com
JID: scottlu@google.com

Joe Hildebrand

Email: jhildebrand@jabber.com
JID: hildjj@jabber.org

1. Introduction

2. Requirements

3. Protocol Description

3.1. Transport Initiation

3.2. Target Entity Response

3.3. Informational Messages

4. Security Considerations

4.1. End-to-End Data Encryption

5. IANA Considerations

6. Jabber Registrar Considerations

6.1. Protocol Namespaces

6.2. Jingle Transport Methods

7. XML Schema

Notes

Revision History

3.1 Transport Initiation

In order for the initiating entity in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in JEP-0166. This stanza MUST include at least one transport methods. If the initiating entity wishes to negotiate the Raw UDP transport, it MUST include an empty <transport/> child element qualified by the 'http://jabber.org/protocol/jingle/transport/raw-udp' namespace.

This <transport/> element MUST include one and only one <candidate/> element per channel, whose 'ip' and 'port' attributes specify the IP address and port number of the candidate that the initiator has reason to believe will be most likely to succeed for that channel. (Note: In older versions of JEP-0166, this was referrred to as the "default candidate".) This is not necessarily the initiator's preferred address for communication, but instead is the "address most likely to succeed", i.e., the address that is assumed to be reachable by the vast majority of target entities. To determine reachability, the client needs classify ahead of time the permissiveness of the firewall or network address translator (NAT) it is behind, if any. If the NAT is symmetric (not permissive), the candidate SHOULD specify a relay address. Otherwise it SHOULD be an address derived via prior discovery using RFC 3489 [4], which will be an address on the outside of the firewall or NAT.

Example 1. Initiation Example

<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='jingle1' type='set'>
  <jingle xmlns='http://jabber.org/protocol/jingle' 
          action='session-initiate' 
          initiator='romeo@montague.net/orchard'
          sid='a73sjjvkla37jfea'>
    <description ...>
    <transport xmlns='http://jabber.org/protocol/jingle/transport/raw-udp'>
      <candidate name='myvoicedata' ip='10.1.1.104' port='13540' generation='0'/>
    </transport>
  </jingle>
</iq>
    

Note: The 'name' attribute specifies the name of the channel and the 'generation' attribute provides a tracking mechanism for determining which version of this candidate is in force (this is useful if the candidate is redefined mid-stream, for example if the port is changed).

3.2 Target Entity Response

As described in JEP-0166, to provisionally accept the session initiation request, the target entity returns an IQ-result:

Example 2. Target Entity Provisionally Accepts the Session Request

<iq type='result' from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='jingle1'/>
    

To accept the Raw UDP transport method, the target entity MUST send a <jingle/> element with an action of 'transport-accept', specifying the transport method desired.

Example 3. Target Entity Accepts the Raw UDP Transport Method

<iq type='set' from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='jingle2'>
  <jingle xmlns='http://jabber.org/protocol/jingle' 
          action='transport-accept' 
          initiator='romeo@montague.net/orchard'
          sid='a73sjjvkla37jfea'>
    <transport xmlns='http://jabber.org/protocol/jingle/transport/raw-udp'>
      <candidate ip='10.1.1.104' port='13540'/>
    </transport>
  </jingle>
</iq>
    

3.3 Informational Messages

The syntax and semantics informational message payloads specific to the Raw UDP transport method will be defined in a future version of this specification.

4.1 End-to-End Data Encryption

In order to secure the end-to-end data stream, implementations SHOULD use native RTP encryption methods, such as ZRTP [5] or RTP Over DTLS [6].

6.1 Protocol Namespaces

The Jabber Registrar [8] shall include 'http://jabber.org/protocol/jingle/transport/raw-udp' in its registry of protocol namespaces.

6.2 Jingle Transport Methods

The Jabber Registrar shall include "http://jabber.org/protocol/jingle/transport/raw-udp" in its registry of Jingle transport methods. The registry submission is as follows:

In order to submit new values to this registry, the registrant must define an XML fragment of the following form and either include it in the relevant Jabber Enhancement Proposal or send it to the email address <registrar@jabber.org>:

<transport>
  <name>raw-udp</name>
  <desc>A method for exchanging RTP streams over a raw UDP connection.</desc>
  <doc>JEP-0176</doc>
</transport>
    

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='http://jabber.org/protocol/jingle/transports/raw-udp'
    xmlns='http://jabber.org/protocol/jingle/transports/raw-udp'
    elementFormDefault='qualified'>

  <xs:element name='transport'>
    <xs:complexType>
      <xs:sequence>
        <xs:element ref='candidate' minOccurs='0' maxOccurs='1'/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

  <xs:element name='candidate'>
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base='empty'>
          <xs:attribute name='generation' type='xs:unsignedByte' use='required'/>
          <xs:attribute name='name' type='xs:string' use='required'/>
          <xs:attribute name='ip' type='IPaddress' use='required'/>
          <xs:attribute name='port' type='xs:unsignedShort' use='required'/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

  <xs:simpleType name='IPaddress'>
    <xs:restriction base='xs:string'>
      <xs:pattern value='((1?[0-9]?[0-9]|2[0-4][0-9]|25[0-5]).){3}(1?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])'/>
    </xs:restriction>
  </xs:simpleType>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>
  

1. JEP-0166: Jingle <http://www.jabber.org/jeps/jep-0166.html>.

2. RFC 3550: RTP: A Transport Protocol for Real-Time Applications <http://www.ietf.org/rfc/rfc3550.txt>.

3. RFC 768: User Datagram Protocol <http://www.ietf.org/rfc/rfc0768.txt>.

4. RFC 3489: STUN - Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs) <http://www.ietf.org/rfc/rfc3489.txt>.

5. ZRTP: Extensions to RTP for Diffie-Hellman Key Agreement for SRTP <http://www.ietf.org/internet-drafts/draft-zimmermann-avt-zrtp-01.txt>. Work in progress.

6. Real-Time Transport Protocol (RTP) over Datagram Transport Layer Security (DTLS) <http://scm.sipfoundry.org/rep/ietf-drafts/ekr/draft-tschofenig-avt-rtp-dtls-00.txt>. Work in progress.

7. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>.

8. The Jabber Registrar maintains a list of reserved Jabber protocol namespaces as well as registries of parameters used in the context of protocols approved by the Jabber Software Foundation. For further information, see <http://www.jabber.org/registrar/>.

Version 0.1 (2006-03-01)