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PubSub Server Info: rework Discovering Support

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Instead of basing Discovery of Support on the presence of a well-known pub-sub service node, an explicit Service Discovery feature is used. This prevents a scenario in which a non-administrative user flags 'opt-in' by creating the pub-sub node.
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Guus der Kinderen 2023-12-20 18:53:48 +01:00
parent 7e82fc1fd0
commit e7fcb86c91
1 changed files with 60 additions and 8 deletions
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inbox/pubsub-server-info.xml
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@ -45,8 +45,40 @@
</ul>
</section1>
<section1 topic="Discovering Support" anchor="disco">
<p>Support is advertised by publishing a first-level leaf node using the name 'serverinfo' on a pub-sub service. An entity trying to discover support will, for a given domain name, use &xep0030; to identify a Publish-Subscribe service for the domain, and subsequently use service discovery to discover the node with name 'serverinfo' as defined in section 5.3 of &xep0060;.</p>
<example caption="Entity queries collection node for information"><![CDATA[
<p>Domains supporting the publication of Server Information data, as described in this document, MUST advertise the fact by announcing a &xep0030; feature of 'urn:xmpp:serverinfo:0'. This signifies that an administrative entity approved the publication of data, which is important for the opt-in mechanism described in <link url="#privacy">Privacy Considerations section</link> of this document.</p>
<p>The pub-sub service address and node in which Server Information data is advertised SHOULD be specified using a &xep0128;. These pub-sub coordinates MUST be scoped using a FORM_TYPE of "http://jabber.org/network/serverinfo" (as already specified in XEP-0128) and data form fields registered for this purpose as defined in the <link url="#registrar">XMPP Registrar Considerations section</link> of this document.</p>
<p>When the 'urn:xmpp:serverinfo:0' feature but no corresponding Service Discovery Extension is advertised, the node that is used will be a first-level leaf node using the name 'serverinfo' on the first pub-sub service advertised through service discovery.</p>
<example caption="Service Discovery information request"><![CDATA[
<iq type='get'
from='francisco@denmark.lit/barracks'
to='shakespeare.lit'
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>]]></example>
<example caption="Service Discovery information response"><![CDATA[
<iq type='result'
from='shakespeare.lit'
to='francisco@denmark.lit/barracks'
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='urn:xmpp:serverinfo:0'/>
...
<x xmlns='jabber:x:data' type='result'>
<field var='FORM_TYPE' type='hidden'>
<value>http://jabber.org/network/serverinfo</value>
</field>
<field var='serverinfo-pubsub-service'>
<value>pubsub.shakespeare.lit</value>
</field>
<field var='serverinfo-pubsub-node'>
<value>serverinfo</value>
</field>
</x>
</query>
</iq>]]></example>
<p>The node MUST reference a first-level leaf node on a pub-sub service.</p>
<example caption="Entity queries root node for information"><![CDATA[
<iq type='get'
from='francisco@denmark.lit/barracks'
to='pubsub.shakespeare.lit'
@ -138,18 +170,38 @@
<p>As certain information can be expected to be updated continuously and frequently, the server MAY choose to reduce the frequency of updates of the 'serverinfo' pub-sub node.</p>
</section1>
<section1 topic="Privacy Considerations" anchor="privacy">
<p>When multiple domains publish their connections to named remote domains, an information leak occurs: by collecting these public statistics, behavioral data of those remote domains can be deduced. To prevent undesired privacy-sensitive information leaks, a domain MUST NOT publish the name of a remote domain, unless that domain advertises support for this XEP.</p>
</section1>
<section1 topic="IANA Considerations" anchor="iana">
<p>This document requires no interaction with the &IANA;</p>
<p>When multiple domains publish their connections to named remote domains, an information leak occurs: by collecting these public statistics, behavioral data of those remote domains can be deduced. To prevent undesired privacy-sensitive information leaks, a domain MUST NOT publish the name of a remote domain, unless that domain advertises support for this XEP, as defined in the <link url="#disco">Discovering Support section</link> of this document.</p>
<p>This way, the service discovery mechanism doubles as an opt-in mechanism. Domains that advertise support for this XEP allow other domains to reference them by domain-name in the data that they publish. The mere presence of an applicable pub-sub node MUST NOT be used for Service Discovery purposes, as under common service configuration, non-administrative users are allowed to create such nodes.</p>
</section1>
<section1 topic="XMPP Registrar Considerations" anchor="registrar">
<p>Upon advancement of this specification from a status of Experimental to a status of Draft, the &REGISTRAR; shall include the following information in its registries.</p>
<section2 topic="Protocol Namespaces" anchor="registrar-ns">
<p>This specification defines the following XML namespaces:</p>
<ul>
<li>urn:xmpp:serverinfo:0</li>
</ul>
<p>Upon advancement of this specification from a status of Experimental to a status of Draft, the &REGISTRAR; shall add the foregoing namespace to the registry located at &NAMESPACES;, as described in Section 4 of &xep0053;.</p>
<p>The &REGISTRAR; shall add the foregoing namespace to the registry located at &NAMESPACES;, as described in Section 4 of &xep0053;.</p>
</section2>
<section2 topic='Field Standardization' anchor='registrar-formtype'>
<p>&xep0068; defines a process for standardizing the fields used within Data Forms qualified by a particular namespace, and <cite>XEP-0128</cite> describes how to use field standardization in the context of service discovery. This section registers fields for server information scoped by the "http://jabber.org/network/serverinfo" FORM_TYPE.</p>
<code caption='Registry Submission'><![CDATA[
<form_type>
<name>http://jabber.org/network/serverinfo</name>
<doc>XEP-0XXX</doc>
<desc>
Forms advertising the coordinates of a pub-sub service and node for publication of Server Information data.
</desc>
<field
var='serverinfo-pubsub-service'
type='list-multi'
label='The address of a pub-sub service that hosts a node on which Server Information data is published.'/>
<field
var='serverinfo-pubsub-node'
type='list-multi'
label='A nodeId on which Server Information data is published.'/>
</form_type>
]]></code>
<p>Note that the FORM_TYPE used by &xep0157; is purposefully re-used by this XEP, to circumvent the restriction of having at most one XMPP Standards Foundation defined FORM_TYPE for a service discovery identity, as defined in &xep0128;. When a service supports both features, the data in both forms SHOULD be merged into one form.</p>
</section2>
</section1>
<section1 topic='XML Schema' anchor='schema'>
@ -217,7 +269,7 @@
]]></code>
</section1>
<section1 topic='Acknowledgements' anchor='acknowledgements'>
<p>Inspiration was taken from the (now defunct) 'server info' crawler by Thomas Leister. Many thanks to Dave Cridland, as well as 'zoidberg' and 'chewie' from the Ignite Realtime community for helping to test the initial implementation of a graphing implementation based on this XEP and to Florian Schmaus, Matthew Wild and Jonas Schäfer for their feedback on the earliest drafts of this document.</p>
<p>Inspiration was taken from the (now defunct) 'server info' crawler by Thomas Leister. Many thanks to Dave Cridland, as well as 'zoidberg' and 'chewie' from the Ignite Realtime community for helping to test the initial implementation of a graphing implementation based on this XEP and to Florian Schmaus, Matthew Wild, Jonas Schäfer and Kevin Smith for their feedback on the earliest drafts of this document.</p>
</section1>
</xep>