XEP-0177: Jingle Raw UDP Transport

Joe Beda

Email: jbeda@google.com
JabberID: jbeda@google.com

Peter Saint-Andre

Email: stpeter@jabber.org
JabberID: stpeter@jabber.org

Scott Ludwig

Email: scottlu@google.com
JabberID: scottlu@google.com

Joe Hildebrand

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

Sean Egan

Email: seanegan@google.com
JabberID: seanegan@google.com

1. Introduction
2. Requirements
3. Protocol Description
    3.1. Transport Initiation
    3.2. Responder Response
       3.2.1. Checking the Initiator's Candidate
       3.2.2. Sending A Candidate
       3.2.3. Sending An Informational Message
    3.3. Informational Messages
4. Security Considerations
5. IANA Considerations
6. XMPP 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 initiator in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in XEP-0166. This stanza MUST include at least one content type. If the initiator wishes to negotiate the Raw UDP transport for a given content type, it MUST include a <transport/> child element qualified by the 'http://www.xmpp.org/extensions/xep-0177.html#ns' namespace (see Protocol Namespaces), which MUST [5] include the initiator's Raw UDP candidate via the 'ip', 'port', 'generation', and 'name' attributes of the <candidate/> element.

Example 1. Initiation Example

<iq from='romeo@montague.net/orchard' to='juliet@capulet.com/balcony' id='jingle1' type='set'>
  <jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
          action='session-initiate'
          initiator='romeo@montague.net/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <description ...>
      <transport xmlns='http://www.xmpp.org/extensions/xep-0177.html#ns'>
        <candidate ip='10.1.1.104' port='13540' generation='0'/>
      </transport>
    </content>
  </jingle>
</iq>
    

The 'generation', 'ip', and 'port' attributes are REQUIRED. The 'ip' and 'port' attributes are self-explanatory. 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).

Note: The "Raw UDP candidate" is the candidate that the entity has reason to believe will be most likely to succeed for that content type, and thus is equivalent to the "in-use" candidate as described in Interactive Connectivity Establishment (ICE) [6]. [7] This is not necessarily the entity'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 NAT or firewall it is behind, if any. It then SHOULD assign the Raw UDP candidate as follows, where the candidate types are as described in ICE:

Table 1: Raw UDP Candidate Assignment

3.2 Responder Response

As described in XEP-0166, to provisionally accept the session initiation request, the receiver returns an IQ-result:

Example 2. Responder Provisionally Accepts the Session Request

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

Once the responder provisionally accepts the session, it:

• MUST check the initiator's Raw UDP candidate by attempting to send data via UDP to the specified IP and port (see next section).
• SHOULD send its own Raw UDP candidate to the initiator via a Jingle "transport-info" message.
• MAY send an informational message.

These are done simultaneously in order to ensure that a connection can be made, since the initiator's Raw UDP candidate may not result in success.

<iq from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' type='set' id='accept1'>
  <jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
          action='content-accept'
          initiator='romeo@montague.net/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='http://www.xmpp.org/extensions/xep-0177.html#ns'>
        <candidate name='myvoicedata' ip='10.1.1.104' port='13540' generation='0'/>
      </transport>
    </content>
  </jingle>
</iq>
      

<iq from='romeo@montague.net/orchard' to='juliet@capulet.com/balcony' type='result' id='accept1'/>
      

<iq from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='jingle2' type='set'>
  <jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
          action='transport-info'
          initiator='romeo@montague.net/orchard'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='http://www.xmpp.org/extensions/xep-0177.html#ns'>
        <candidate ip='208.245.212.67' port='9876' generation='0'/>
      </transport>
    </content>
  </jingle>
</iq>
      

<iq from='romeo@montague.net/orchard' to='juliet@capulet.com/balcony' type='result' id='jingle2'/>
      

3.3 Informational Messages

Informational messages MAY be sent by the receiver within the context of the Raw UDP transport to communicate the status of transport checking. The informational message MUST be an IQ-set containing a <jingle/> element of type "session-info", where the informational message is a payload element qualified by the 'http://www.xmpp.org/extensions/xep-0177.html#ns-info' namespace (see Protocol Namespaces). The following payload elements are defined:

Table 2: Information Payload Elements

Note: Because the informational message is sent in an IQ-set, the receiving party MUST return either an IQ-result or an IQ-error (normally only an IQ-result to acknowledge receipt; no error flows are defined or envisioned at this time).

6.1 Protocol Namespaces

Until this specification advances to a status of Draft, its associated namespaces shall be "http://www.xmpp.org/extensions/xep-0177.html#ns" and "http://www.xmpp.org/extensions/xep-0177.html#ns-info"; upon advancement of this specification, the XMPP Registrar [11] shall issue permanent namespaces in accordance with the process defined in Section 4 of XMPP Registrar Function [12].

6.2 Jingle Transport Methods

The XMPP Registrar shall include "raw-udp" in its registry of Jingle transport methods. The registry submission is as follows:

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

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

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='http://www.xmpp.org/extensions/xep-0177.html#ns'
    xmlns='http://www.xmpp.org/extensions/xep-0177.html#ns'
    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='ip' type='xs:string' use='required'/>
          <xs:attribute name='port' type='xs:unsignedShort' use='required'/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>

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

</xs:schema>
  

1. XEP-0166: Jingle <http://www.xmpp.org/extensions/xep-0166.html>.

2. RFC 768: User Datagram Protocol <http://tools.ietf.org/html/rfc0768>.

3. This is also helpful for bootstrapping of Jingle implementation by developers working on a local network.

4. XEP-0176: Jingle ICE Transport Method <http://www.xmpp.org/extensions/xep-0176.html>.

5. This is required to avoid a round trip and help expedite the negotiation.

6. Interactive Connectivity Establishment (ICE): A Methodology for Network Address Translator (NAT) Traversal for Offer/Answer Protocols <http://www.ietf.org/internet-drafts/draft-ietf-mmusic-ice-14.txt>. Work in progress.

7. In older versions of XEP-0166, this was referrred to as the "default candidate".

8. RFC 3489: STUN - Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs) <http://tools.ietf.org/html/rfc3489>.

9. RFC 862: Echo Protocol <http://tools.ietf.org/html/rfc0862>.

10. 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/>.

11. The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the XMPP Standards Foundation. For further information, see <http://www.xmpp.org/registrar/>.

12. XEP-0053: XMPP Registrar Function <http://www.xmpp.org/extensions/xep-0053.html>.

Version 0.5 (2007-03-23)

Version 0.4 (2006-12-21)

Version 0.3 (2006-10-31)

Version 0.2 (2006-07-12)

Version 0.1 (2006-03-01)