XEP-0371: Jingle ICE Transport Method

1. Introduction
2. Glossary
3. Requirements
4. Jingle Conformance
5. Protocol Description
    5.1. Overall Flow
    5.2. Session Initiation
    5.3. Syntax
    5.4. Response
    5.5. Candidate Negotiation
    5.6. Connectivity Checks
    5.7. End-of-Candidates Indication
    5.8. Acceptance of Successful Candidate
    5.9. Negotiating a New Candidate
    5.10. ICE Restarts
6. Fallback to Raw UDP
7. Informational Messages
8. Determining Support
    8.1. ICE Support
    8.2. SDP Offer / Answer Support
9. Implementation Notes
10. Deployment Notes
11. Security Considerations
    11.1. Sharing IP Addresses
    11.2. Encryption of Media
12. IANA Considerations
13. XMPP Registrar Considerations
    13.1. Protocol Namespaces
    13.2. Protocol Versioning
    13.3. Service Discovery Features
    13.4. Jingle Transport Methods
14. XML Schema
15. Acknowledgements

Appendices
    A: Document Information
    B: Author Information
    C: Legal Notices
    D: Relation to XMPP
    E: Discussion Venue
    F: Requirements Conformance
    G: Notes
    H: Revision History

5.1 Overall Flow

The overall protocol flow for negotiation of the Jingle ICE Transport Method is as follows (note: many of these events happen simultaneously, not in sequence).

INITIATOR                              RESPONDER
    |                                      |
    |  Jingle session-initiate stanza      |
    |  (with zero or more candidates)      |
    |------------------------------------->|
    |  Jingle ack (XMPP IQ-result)         |
    |<-------------------------------------|
    |  Jingle session-accept stanza        |
    |  (with one or more candidates)       |
    |<-------------------------------------|
    |  Jingle ack (XMPP IQ-result)         |
    |------------------------------------->|
    |  multiple STUN Binding Requests      |
    |<====================================>|
    |  multiple STUN Binding Results       |
    |<====================================>|
    |<=========MEDIA NOW FLOWS============>|
    |  optional Jingle transport-info      |
    |  stanzas (one candidate per stanza)  |
    |<------------------------------------>|
    |                                      |
    

Note: The examples in this document follow the scenario described in Section 17 of RFC 5245, except that we substitute the Shakespearean characters "Romeo" and "Juliet" for the generic entities "L" and "R".

5.2 Session Initiation

In order for the initiator in a Jingle exchange to start the negotiation, it sends a Jingle "session-initiate" stanza that includes at least one content type, as described in XEP-0166. If the initiator wishes to negotiate the ICE transport method for an application format, it MUST include a <transport/> child element qualified by the 'urn:xmpp:jingle:transports:ice:0' namespace (see Namespace Versioning regarding the possibility of incrementing the version number). This element SHOULD in turn contain one <candidate/> element for each of the initiator's higher-priority transport candidates as determined in accordance with the ICE methodology, but MAY instead be empty (with each candidate to be sent as the payload of a transport-info message).

Example 1. Initiation

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='ixt174g9'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='0' name='PCMU' />
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice:0'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='2B78DADC1A9E'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='58AA96B8FA5A'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>
    

5.3 Syntax

The <transport/> element's 'pwd' and 'ufrag' attributes MUST be included whenever sending one or more candidates to the other party, e.g., in a session-initiate, session-accept, transport-info, content-add, or transport-replace message. The values for these attributes are separately generated for both the initiator and the responder, in accordance with RFC 5245 and as shown in the examples. The attributes of the <transport/> element are as follows.

The attributes of the <candidate/> element are as follows.

Note this specification does not provide an equivalent of the "ice-options" attribute defined in Section 15.5 of RFC 5245, since it is not needed in XMPP given the existence of the Service Discovery extension (XEP-0030).

5.4 Response

As described in XEP-0166, to acknowledge receipt of the session initiation request, the responder immediately returns an IQ-result.

Example 2. Responder acknowledges receipt of session-initiate request

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='ixt174g9'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'/>
    

Depending on the application type, a user agent controlled by a human user might need to wait for the user to affirm a desire to proceed with the session before continuing. When the user agent has received such affirmation (or if the user agent can automatically proceed for any reason, e.g., because no human intervention is expected or because a human user has configured the user agent to automatically accept sessions with a given entity), it returns a Jingle session-accept message. This message MUST contain a <transport/> element qualified by the 'urn:xmpp:jingle:transports:ice:0' namespace, which SHOULD in turn contain one <candidate/> element for each ICE candidate generated by or known to the responder, but MAY instead be empty (with each candidate to be sent as the payload of a transport-info message).

Note: See the Security Considerations section of this document regarding the exposure of IP addresses by the responder's client.

Example 3. Responder accepts the session request

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='rw782g55'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          responder='juliet@capulet.example/yn0cl4bnw0yr3vym'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice:0'
                 pwd='YH75Fviy6338Vbrhrlp8Yh'
                 ufrag='9uB6'>
        <candidate component='1'
                   foundation='2B78DADC1A9E'
                   generation='0'
                   id='or2ii2syr1'
                   ip='192.0.2.1'
                   network='0'
                   port='3478'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>
    

5.5 Candidate Negotiation

The initiator and responder negotiate connectivity over ICE by exchanging XML-formatted transport candidates for the channel. This negotiation proceeds immediately in order to maximize the possibility that connectivity can be established (and therefore media can be exchanged) as quickly as possible. In order to expedite session establishment, the initiator SHOULD include transport candidates in its session-initiate message but MAY also send additional transport candidates as soon as it learns of them, even before receiving the IQ-result that acknowledges the session-initiate message (i.e., the initiator MUST consider the session to be live as soon as it sends the session-initiate message). [12]

The first step in negotiating connectivity is for each party to send transport candidates to the other party. [14] These candidates SHOULD be gathered by following the procedure specified in Section 4.1.1 of RFC 5245 (typically by communicating with a standalone STUN server in order to discover the client's public IP address and port) and prioritized by following the procedure specified in Section 4.1.2 of RFC 5245.

Each candidate shall be sent as a <candidate/> child of a <transport/> element qualified by the 'urn:xmpp:jingle:transports:ice:0' namespace. The <transport/> element is sent via a Jingle message of type session-initiate, session-accept, or transport-info.

Either party MAY include multiple <candidate/> elements in one <transport/> element, especially in the session-initiate and session-accept messages sent at the beginning of the session negotiation. Including multiple candidates in the session-initiate and session-accept messages can help to ensure interoperability with entities that implement the SDP offer/answer model described in RFC 3264; in particular, an entity SHOULD include multiple candidates in its session-initiate or session-accept message if the other party advertises support for the "urn:ietf:rfc:3264" service discovery feature as described in the SDP Offer / Answer Support section of this document. However, including one candidate per subsequent transport-info message typically results in a faster negotiation because the candidates most likely to succeed are sent first (in the session-info and session-accept messages) and it is not necessary to gather all candidates before beginning to send any candidates; furthermore, because certain candidates can be more "expensive" in terms of bandwidth or processing power, either party might not want to advertise the existence of such candidates unless it is necessary to do so after other candidates have failed.

If the party that receives a candidate in a Jingle message can successfully process a given candidate or set of candidates, it returns an IQ-result (if not, for example because the candidate data is improperly formatted, it returns an IQ-error). At this point, the receiving entity is only indicating receipt of the candidate or set of candidates, not telling the other party that the candidate will be used.

The initiator can keep sending candidates (without stopping to receive an acknowledgement of receipt from the responder for each candidate) until it has exhausted its supply of possible or desirable transport candidates. The responder can also keep sending potential candidates, which the initiator will acknowledge.

5.6 Connectivity Checks

As the initiator and responder receive candidates, they probe the candidates for connectivity. In performing these connectivity checks, each party SHOULD follow the procedure specified in Section 7 of RFC 5245. The following business rules apply:

1. Each party sends a STUN Binding Request (see RFC 5389 [15]) from each local candidate it generated to each remote candidate it received.
2. In accordance with RFC 5245, the STUN Binding Requests MUST include the PRIORITY attribute (computed according to Section 7.1.1.1. of RFC 5245).
3. For the purposes of the Jingle ICE Transport Method, both parties are full ICE implementations and therefore the controlling role MUST be assumed by the initiator and the controlled role MUST be assumed by the responder.
4. The STUN Binding Requests generated by the initiator MAY include the USE-CANDIDATE attribute to indicate that the initiator wishes to cease checks for this component.
5. The STUN Binding Requests generated by the initiator MUST include the ICE-CONTROLLING attribute.
6. The STUN Binding Requests generated by the responder MUST include the ICE-CONTROLLED attribute.
7. The parties MUST use STUN short term credentials to authenticate requests and perform message integrity checks. As in RFC 5245, the username in the STUN Binding Request is of the form "ufrag-of-peer:ufrag-of-sender" and the password is the value of the 'pwd' attribute provided by the peer. [16]

When it receives a STUN Binding Request, each party MUST return a STUN Binding Response, which indicates either an error case or the success case. As described in Section 7.1.2.2 of RFC 5245, a connectivity check succeeds if all of the following are true:

1. The STUN transaction generated a success response.
2. The source IP address and port of the response equals the destination IP address and port to which the Binding Request was sent.
3. The destination IP address and port of the response match the source IP address and port from which the Binding Request was sent.

For the candidates exchanged in the previous section, the connectivity checks would be as follows (this diagram mirrors the example in RFC 5245).

INITIATOR                  NAT                  RESPONDER
    |                       |                       |
    |                       | STUN Binding Request  |
    |                       | from 192.0.2.1:3478   |
    |                       | to   10.0.1.1:8998    |
    |                       |   (dropped)           |
    |                       |  x====================|
    | STUN Binding Request  |                       |
    | from 10.0.1.1:8998    |                       |
    | to   192.0.2.1:3478   |                       |
    | USE-CANDIDATE         |                       |
    |======================>|                       |
    |                       | STUN Binding Request  |
    |                       | from 192.0.2.3:45664  |
    |                       | to   192.0.2.1:3478   |
    |                       | USE-CANDIDATE         |
    |                       |======================>|
    |                       | STUN Binding Response |
    |                       | from 192.0.2.1:3478   |
    |                       | to   192.0.2.3:45664  |
    |                       |<======================|
    | STUN Binding Response |                       |
    | from 192.0.2.1:3478   |                       |
    | to   10.0.1.1:8998    |                       |
    | map  192.0.2.3:45664  |                       |
    |<======================|                       |
    |                       |                       |
    |<==Media Now Can Flow==|                       |
    |                       |                       |
    |                       | STUN Binding Request  |
    |                       | from 192.0.2.1:3478   |
    |                       | to   192.0.2.3:45664  |
    |                       |<======================|
    | STUN Binding Request  |                       |
    | from 192.0.2.1:3478   |                       |
    | to   10.0.1.1:8998    |                       |
    |<======================|                       |
    | STUN Binding Response |                       |
    | from 10.0.1.1:8998    |                       |
    | to   192.0.2.1:3478   |                       |
    | map  192.0.2.1:3478   |                       |
    |======================>|                       |
    |                       | STUN Binding Response |
    |                       | from 192.0.2.3:45664  |
    |                       | to   192.0.2.1:3478   |
    |                       | map  192.0.2.1:3478   |
    |                       |======================>|
    |                       |                       |
    |                       |==Media Now Can Flow==>|
    |                       |                       |
    

Note: Here the initiator (controlling agent) is using "aggressive nomination" as described in Section 8.1.1.2 of RFC 5245 and therefore includes the USE-CANDIDATE attribute in the STUN Binding Requests it sends.

5.7 End-of-Candidates Indication

As explained in the Trickle ICE specification, when a party has completed gathering of ICE candidates it will send an "end-of-candidates indication" to the other party. In Jingle, this takes the form of an informational message as described under Informational Messages. This specificaton defines only a standalone "end-of-candidates indication" (i.e., not a way to indicate ICE completion in an offer or answer).

5.8 Acceptance of Successful Candidate

If, based on STUN connectivity checks, the parties determine that they will be able to exchange media between a given pair of local candidates and remote candidates (i.e., the pair is "nominated" and ICE processing is "completed"), they can then begin using that candidate pair to exchange media.

Once the parties have connectivity and therefore the initiator has completed ICE as explained in RFC 5245, the initiator MAY communicate the in-use candidate pair in the signalling channel by sending a transport-info message that contains a <remote-candidate/> element (this maps to the SDP "remote-candidates" attribute as described in Section B.6 of RFC 5245, i.e., remote candidates are "the actual candidates at R that were selected by the offerer", of which there will be only one at this stage of the ICE negotiation).

Example 4. Initiator communicates in-use candidate

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='pd81b49s'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='set'>
 <jingle xmlns='urn:xmpp:jingle:1'
         action='transport-info'
         initiator='romeo@montague.example/dr4hcr0st3lup4c'
         sid='a73sjjvkla37jfea'>
   <content creator='initiator' name='this-is-the-audio-content'>
     <transport xmlns='urn:xmpp:jingle:transports:ice:0'
                pwd='asd88fgpdd777uzjYhagZg'
                ufrag='8hhy'>
       <remote-candidate component='1'
                         ip='10.0.1.2'
                         port='9001'/>
     </transport>
   </content>
 </jingle>
</iq>
    

(In accordance with Jingle core, the responder will also acknowledge the transport-info message.)

In the unlikely event that one of the parties determines that it cannot establish connectivity even after sending and checking lower-priority candidates, it SHOULD terminate the session as described in XEP-0166.

5.9 Negotiating a New Candidate

Even after media has begun to flow, either party MAY continue to send additional candidates to the other party (e.g., because the user agent has become aware of a new media proxy or network interface card). Such candidates are shared by sending a transport-info message.

Example 5. Initiator sends a subsequent candidate

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='uh3g1f48'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-info'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='urn:xmpp:jingle:transports:ice:0'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='2B78DADC1A9E'
                   generation='0'
                   id='m3110wc4nd'
                   ip='2001:db8::9:1'
                   network='0'
                   port='9001'
                   priority='21149780477'
                   protocol='udp'
                   type='host'/>
      </transport>
    </content>
  </jingle>
</iq>
    

The receiving party MUST acknowledge receipt of the candidate.

Example 6. Recipient acknowledges receipt

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='uh3g1f48'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'/>
    

The parties would check the newly-offered candidate for connectivity, as described previously. If the parties determine that media can flow over the candidate, they MAY then use the new candidate in subsequent communications.

5.10 ICE Restarts

At any time, either party MAY restart the process of ICE negotiation by sending a candidate with a 'generation' value that is greater than the previous generation of candidates; when it does so, it MUST generate new values for the 'pwd' and 'ufrag' attributes, consistent with the definition of an ICE restart in Section 9.1.1.1 of RFC 5245 (because an ICE restart is signalled by a change in the 'pwd' and 'ufrag' attributes, strictly speaking the 'generation' attribute is not absolutely necessary). As explained in RFC 5245, typically the ICE negotiation would be restarted to change the media target (e.g., an IP address change for one of the parties) and certain third-party-call-control scenarios.

Example 7. Initiator restarts ICE negotiation

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='kl23fs71'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-info'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='urn:xmpp:jingle:transports:ice:0'
                 pwd='bv71hdn38hgb39hf6xlk33'
                 ufrag='g7qs'>
        <candidate component='1'
                   foundation='2B78DADC1A9E'
                   generation='1'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45665'
                   priority='1694498815'
                   protocol='udp'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>
    

The recipient then acknowledges receipt.

Example 8. Recipient acknowledges transport-info

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='kl23fs71'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'/>
    

The parties would then exchange new candidates to renegotiate connectivity and would check the new candidates for connectivity, as described previously. If the parties determine that media can flow over one of the new candidates, they can then use the successful candidate in subsequent communications. However, while ICE is being renegotiated the parties can continue to send media with the existing candidate-in-use.

Romeo                    Gateway                    Juliet
  |                         |                         |
  |   session-initiate      |                         |
  |   (audio definition)    |                         |
  |------------------------>|                         |
  |   ack                   |                         |
  |<------------------------|                         |
  |   transport-replace     |                         |
  |   (Raw UDP)             |                         |
  |<------------------------|                         |
  |   ack                   |                         |
  |------------------------>|                         |
  |   transport-accept      |                         |
  |------------------------>|                         |
  |   ack                   |                         |
  |<------------------------|   SIP INVITE            |
  |                         |------------------------>|
  |                         |   200 OK                |
  |                         |<------------------------|
  |   session-accept        |                         |
  |<------------------------|                         |
  |   ack                   |                         |
  |------------------------>|                         |
  |                    MEDIA SESSION                  |
  |<=================================================>|
  |                         |   SIP BYE               |
  |                         |<------------------------|
  |   session-terminate     |                         |
  |<------------------------|                         |
  |   ack                   |                         |
  |------------------------>|   ack                   |
  |                         |------------------------>|
  |                         |                         |
    

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='p01hf63x'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='96' name='speex' clockrate='16000'/>
        <payload-type id='97' name='speex' clockrate='8000'/>
        <payload-type id='18' name='G729'/>
        <payload-type id='103' name='L16' clockrate='16000' channels='2'/>
        <payload-type id='98' name='x-ISAC' clockrate='8000'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:ice:0'
                 pwd='asd88fgpdd777uzjYhagZg'
                 ufrag='8hhy'>
        <candidate component='1'
                   foundation='2B78DADC1A9E'
                   generation='0'
                   id='el0747fg11'
                   ip='10.0.1.1'
                   network='1'
                   port='8998'
                   priority='2130706431'
                   protocol='udp'
                   type='host'/>
        <candidate component='1'
                   foundation='58AA96B8FA5A'
                   generation='0'
                   id='y3s2b30v3r'
                   ip='192.0.2.3'
                   network='1'
                   port='45664'
                   priority='1694498815'
                   protocol='udp'
                   rel-addr='10.0.1.1'
                   rel-port='8998'
                   type='srflx'/>
      </transport>
    </content>
  </jingle>
</iq>
    

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='p01hf63x'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'/>
    

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='hy2gd714'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-replace'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice1'>
      <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'>
        <candidate generation='0'
                   id='a9j3mnbtu1'
                   ip='10.1.1.104'
                   port='13540'/>
      </transport>
    </content>
  </jingle>
</iq>
    

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='hy2gd714'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='result'/>
    

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='rb391gs5'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-accept'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='responder' name='voice2'>
      <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'>
        <candidate generation='0'
                   id='a9j3mnbtu1'
                   ip='10.1.1.104'
                   port='13540'/>
      </transport>
    </content>
  </jingle>
</iq>
    

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='rb391gs5'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'/>
    

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='ijf61d43'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-accept'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          responder='juliet@capulet.example/yn0cl4bnw0yr3vym'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='voice'>
      <description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'>
        <payload-type id='18' name='G729'/>
      </description>
      <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'/>
    </content>
  </jingle>
</iq>
    

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='ijf61d43'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='result'/>
    

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='xv39z423'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='set'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='transport-info'
          initiator='romeo@montague.example/dr4hcr0st3lup4c'
          sid='a73sjjvkla37jfea'>
    <content creator='initiator' name='this-is-the-audio-content'>
      <transport xmlns='urn:xmpp:jingle:transports:ice:0'>
        <gathering-complete/>
      </transport>
    </content>
  </jingle>
</iq>
  

8.1 ICE Support

To advertise its support for the Jingle ICE Transport Method, when replying to Service Discovery (XEP-0030) [18] information requests an entity MUST return URNs for any version of this protocol that the entity supports -- e.g., "urn:xmpp:jingle:transports:ice:0" for this version (and "urn:xmpp:jingle:transports:ice-udp:1" for the "ICE-UDP" version previously specified in XEP-0176 (see Namespace Versioning regarding the possibility of incrementing the version number).

Example 18. Service discovery information request

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='cv5x41g9'
    to='juliet@capulet.example/yn0cl4bnw0yr3vym'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
  

Example 19. Service discovery information response

<iq from='juliet@capulet.example/yn0cl4bnw0yr3vym'
    id='cv5x41g9'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:xmpp:jingle:1'/>
    <feature var='urn:xmpp:jingle:transports:ice:0'/>
    <feature var='urn:xmpp:jingle:transports:ice-udp:1'/>
    <feature var='urn:xmpp:jingle:apps:rtp:1'/>
    <feature var='urn:xmpp:jingle:apps:rtp:audio'/>
    <feature var='urn:xmpp:jingle:apps:rtp:video'/>
  </query>
</iq>
    

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in Entity Capabilities (XEP-0115) [19]. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

8.2 SDP Offer / Answer Support

If an entity supports the SDP offer / answer model described in RFC 3264 and therefore prefers to receive multiple candidates in a single transport-info message, it MUST advertise support for the "urn:ietf:rfc:3264" service discovery feature. Typically this feature will be advertised only by gateways between Jingle and SIP.

Example 20. Service discovery information request

<iq from='romeo@montague.example/dr4hcr0st3lup4c'
    id='ce81f5d6'
    to='sip.shakespeare.lit'
    type='get'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
  

Example 21. Service discovery information response

<iq from='sip.shakespeare.lit'
    id='ce81f5d6'
    to='romeo@montague.example/dr4hcr0st3lup4c'
    type='result'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    <feature var='urn:ietf:rfc:3264'/>
    <feature var='urn:xmpp:jingle:1'/>
    <feature var='urn:xmpp:jingle:transports:ice:0'/>
    <feature var='urn:xmpp:jingle:transports:ice-udp:1'/>
    <feature var='urn:xmpp:jingle:apps:rtp:1'/>
    <feature var='urn:xmpp:jingle:apps:rtp:audio'/>
    <feature var='urn:xmpp:jingle:apps:rtp:video'/>
  </query>
</iq>
    

11.1 Sharing IP Addresses

By definition, the exchange of transport candidates results in exposure of the sender's IP addresses, which comprise a form of personally identifying information. A Jingle client MUST enable a user to control which entities will be allowed to receive such information. If a human user explicitly accepts a session request, then the client SHOULD consider that action to imply approval of IP address sharing. However, waiting for a human user to explicitly accept the session request can result in delays during session setup, since it is more efficient to immediately begin sharing transport candidates. Therefore, it is RECOMMENDED for the client to immediately send transport candidates to a contact (without waiting for explicit user approval of the session request) in the following cases:

1. The user has permanently and formally authorized the contact to view the user's presence information via a presence subscription as reflected in an XMPP roster item (see XMPP IM [22]).
2. The user has temporarily and dynamically shared presence with the contact via "directed presence" as described in RFC 3921.
3. The user has explicitly added the contact to a "whitelist" of entities who are allowed to access the user's personally-identifying information.

11.2 Encryption of Media

A Jingle implementation SHOULD support security preconditions that are enforced before application media is allowed to flow over a UDP association, such as those described in Jingle XTLS [23].

Application types that use the Jingle ICE transport method MAY also define their own application-specific encryption methods, such as the Secure Real-time Transport Protocol (SRTP) for RTP exchanges as described in Jingle RTP Sessions (XEP-0167) [24].

13.1 Protocol Namespaces

This specification defines the following XML namespace:

• urn:xmpp:jingle:transports:ice:0

The XMPP Registrar [26] includes the foregoing namespace in its registry at <http://xmpp.org/registrar/namespaces.html>, as governed by XMPP Registrar Function (XEP-0053) [27].

13.2 Protocol Versioning

If the protocol defined in this specification undergoes a revision that is not fully backwards-compatible with an older version, the XMPP Registrar shall increment the protocol version number found at the end of the XML namespaces defined herein, as described in Section 4 of XEP-0053.

13.3 Service Discovery Features

If an entity supports the SDP offer / answer model described in RFC 3264 and therefore prefers to receive one transport-info message with multiple candidates, it MUST advertise support for the "urn:ietf:rfc:3264" feature.

The registry submission is as follows.

Registry Submission

<var>
  <name>urn:ietf:rfc:3264</name>
  <desc>
    Signals support for the SDP offer / answer model 
    described in RFC 3264
  </desc>
  <doc>XEP-0176</doc>
</var>
    

13.4 Jingle Transport Methods

The XMPP Registrar includes "ice" in its registry of Jingle transport methods at <http://xmpp.org/registrar/jingle-transports.html>. The registry submission is as follows:

<transport>
  <name>ice</name>
  <desc>
    A method for negotiation of out-of-band UDP associations 
    or TCP connections with built-in NAT and firewall traversal 
    using the IETF's Interactive Connectivity Establishment (ICE) 
    methodology.
  </desc>
  <type>datagram or streaming</type>
  <doc>XEP-0176</doc>
</transport>
    

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

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='urn:xmpp:jingle:transports:ice:0'
    xmlns='urn:xmpp:jingle:transports:ice:0'
    elementFormDefault='qualified'>

  <xs:annotation>
    <xs:documentation>
      The protocol documented by this schema is defined in
      XEP-0176: http://www.xmpp.org/extensions/xep-0176.html
    </xs:documentation>
  </xs:annotation>

  <xs:element name='transport'>
    <xs:complexType>
      <xs:choice minOccurs='0'>
        <xs:sequence>
          <xs:element name='candidate' 
                      type='candidateElementType'
                      minOccurs='1' 
                      maxOccurs='unbounded'/>
        </xs:sequence>
        <xs:sequence>
          <xs:element name='remote-candidate' 
                      type='remoteCandidateElementType'
                      minOccurs='1' 
                      maxOccurs='1'/>
        </xs:sequence>
        <xs:sequence>
          <xs:any namespace="##other" 
                  processContents="lax"
                  minOccurs="0" 
                  maxOccurs="unbounded"/>
        </xs:sequence>
      </xs:choice>
      <xs:attribute name='pwd' type='xs:string' use='optional'/>
      <xs:attribute name='ufrag' type='xs:string' use='optional'/>
    </xs:complexType>
  </xs:element>

  <xs:complexType name='candidateElementType'>
    <xs:simpleContent>
      <xs:extension base='empty'>
        <xs:attribute name='component' type='xs:unsignedByte' use='required'/>
        <xs:attribute name='foundation' type='xs:string' use='required'/>
        <xs:attribute name='generation' type='xs:unsignedByte' use='optional'/>
        <xs:attribute name='id' type='xs:NCName' use='optional'/>
        <xs:attribute name='ip' type='xs:string' use='required'/>
        <xs:attribute name='network' type='xs:unsignedByte' use='required'/>
        <xs:attribute name='port' type='xs:unsignedShort' use='required'/>
        <xs:attribute name='priority' type='xs:positiveInteger' use='required'/>
        <xs:attribute name='protocol' type='xs:NCName' use='required'/>
        <xs:attribute name='rel-addr' type='xs:string' use='optional'/>
        <xs:attribute name='rel-port' type='xs:unsignedShort' use='optional'/>
        <xs:attribute name='tcptype' use='optional'>
          <xs:simpleType>
            <xs:restriction base='xs:NCName'>
              <xs:enumeration value='active'/>
              <xs:enumeration value='passive'/>
              <xs:enumeration value='so'/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
        <xs:attribute name='type' use='required'>
          <xs:simpleType>
            <xs:restriction base='xs:NCName'>
              <xs:enumeration value='host'/>
              <xs:enumeration value='prflx'/>
              <xs:enumeration value='relay'/>
              <xs:enumeration value='srflx'/>
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>

  <xs:complexType name='remoteCandidateElementType'>
    <xs:simpleContent>
      <xs:extension base='empty'>
        <xs:attribute name='component' 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 name='gathering-complete' type='empty'/>

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

</xs:schema>
  

Peter Saint-Andre

Email: peter@andyet.net
JabberID: stpeter@stpeter.im
URI: https://stpeter.im/

Copyright

Permissions

Disclaimer of Warranty

Limitation of Liability

IPR Conformance

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

2. RFC 5245: Interactive Connectivity Establishment (ICE) <http://tools.ietf.org/html/rfc5245>.

3. Incremental Provisioning of Candidates for the Interactive Connectivity Establishment (ICE) Protocol <http://tools.ietf.org/html/draft-ietf-ice-trickle/>.

4. RFC 4566: SDP: Session Description Protocol <http://tools.ietf.org/html/rfc4566>.

5. RFC 3264: An Offer/Answer Model with the Session Description Protocol (SDP) <http://tools.ietf.org/html/rfc3264>.

6. Incremental Provisioning of Candidates for the Interactive Connectivity Establishment (ICE) Protocol <http://tools.ietf.org/html/draft-ietf-ice-trickle/>.

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

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

9. RFC 6544: TCP Candidates with Interactive Connectivity Establishment (ICE) <http://tools.ietf.org/html/rfc6544>.

10. RFC 793: Transmission Control Protocol <http://tools.ietf.org/html/rfc0793>.

11. In accordance with the rules specified in Section 4.1.1 of RFC 5245, the priority values shown in the examples within this document have been calculated as follows. The "type preference" for host candidates is stipulated to be "126" and for server reflexive candidates "100". The "local preference" for network 0 is stipulated to be "4096", for network 1 "2048", and for network 2 "1024".

12. Given in-order delivery as mandated by XMPP Core [13], the responder will receive such transport-info messages after receiving the session-initiate message; if not, it is appropriate for the responder to return <unknown-session/> errors since according to its state machine the session does not exist.

13. RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core <http://tools.ietf.org/html/rfc6120>.

14. The fact that both parties send candidates means that Jingle requires each party to be a full implementation of ICE, not a lite implementation as specified in RFC 5245.

15. RFC 5389: Session Traversal Utilities for NAT (STUN) <http://tools.ietf.org/html/rfc5389>.

16. Thus when Romeo sends a STUN Binding Request to Juliet the credentials will be STUN username "9uB6:8hhy" (ufrag provided by Juliet concatenated with ufrag provided by Romeo) and password "YH75Fviy6338Vbrhrlp8Yh" (pwd provided by Juliet) whereas when Juliet sends a STUN Binding Request to Romeo the credentials will be STUN username "8hhy:9uB6" (ufrag provided by Romeo concatenated with ufrag provided by Juliet) and password "asd88fgpdd777uzjYhagZg" (pwd provided by Romeo).

17. XEP-0177: Jingle Raw UDP Transport Method <http://xmpp.org/extensions/xep-0177.html>.

18. XEP-0030: Service Discovery <http://xmpp.org/extensions/xep-0030.html>.

19. XEP-0115: Entity Capabilities <http://xmpp.org/extensions/xep-0115.html>.

20. Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN) <http://tools.ietf.org/html/draft-ietf-behave-turn>. Work in progress.

21. XEP-0215: External Service Discovery <http://xmpp.org/extensions/xep-0215.html>.

22. RFC 6121: Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence <http://tools.ietf.org/html/rfc6121>.

23. Extensible Messaging and Presence Protocol (XMPP) End-to-End Encryption Using Transport Layer Security ("XTLS") <http://tools.ietf.org/html/draft-meyer-xmpp-e2e-encryption>.

24. XEP-0167: Jingle RTP Sessions <http://xmpp.org/extensions/xep-0167.html>.

25. 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/>.

26. 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://xmpp.org/registrar/>.

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

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Version 0.0.2 (2015-12-30)

Version 0.0.1 (2015-12-16)