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<p>XMPP components are used for long through &xep0114;, but are quite limited: they have a restricted access to other entities data, similar to what a client can do. This is sufficient for components like gateways, but very limiting for more complex components like a PubSub service. The goal of this XEP is to allow a component or any entity to have a "privileged" status, and access an other entity data with the same privileges than the entity itself, that means send and receive IQ stanzas on its behalf.</p>
<p>Privileged entity have numerous advantages, including:</p>
<li>a step forward in decentralization: it is possible for an entity to do tasks which were before reserved to server itself. For example, a privileged pubsub component can offer access model based on publisher's roster</li>
<li>better integration of components: a gateway can add items to an entity roster itself</li>
<p>In <em>admin</em> mode, the privileged entity MAY be able to emit IQ stanzas in the same way as any entity, including managing roster or accessing persistent storage.</p>
<p>In <em>client</em> mode, a privileged entity MUST have an explicit autorization for any IQ namespace he wants to use. Client SHOULD be able to check and revoke granted permissions, and if it's not possible, permissions MUST be revoked after a disconnection.</p>
<section3topic='Entity request privileged status of admin'anchor='req_status'>
<p>Once the privileged entity is authentified and stream is started, the entity can request its privileged status. It do it by sending an IQ stanza with <strong>'urn:xmpp:privilege:0'</strong> namespace</p>
<p>Namespace permissions are asked with a <perm/> element, which MUST contain a 'namespace' attribute set to the requested namespace and a 'type' attribute which can be:</p>
<ul>
<li><strong>get</strong> — the entity wants to send &IQ; stanza of type <em>'get'</em></li>
<li><strong>set</strong> — the entity wants to send &IQ; stanza of type <em>'set'</em></li>
<li><strong>both</strong> — the entity wants to send &IQ; stanza of type <em>'get'</em> and <em>'set'</em></li>
</ul>
<examplecaption='Entity asks for admin privilege'><![CDATA[
<p>If the server accept the privileged status (e.g.: admin status specified in configuration), it MUST return an IQ result stanza, with allowed permissions in <perm/> elements:</p>
<section2topic='Privileged Entity Send IQ Stanzas'anchor='priv_iq_admin'>
<p>Sending an IQ stanzas is done by sending the stanza the way it would be done by the managed entity, except that its jid is in the 'to' attribute. In the following example, the PubSub service want to know juliet's roster because she own a node with access model based on publiser's roster:</p>
<examplecaption='Privileged Entity Send A Roster Stanza'><![CDATA[
<p>In the following example, the sync.capulet.net privileged entity want to access managed entity's bookmarks to synchronize them with an online service. It can request the bookmarks in the following way:</p>
<p>In <em>client</em> mode, the privileged entity is not certified by the server administrator, so the permissions MUST be <strong>explicitly</strong> allowed by the managed entity. This is initiated by the privileged entity (it can be after an interaction with a managed entity, like a subscription). It's done in the same way as for <em>admin</em> mode with the following exceptions:</p>
<p>Once received the permission request, the server ask to the client if it grant access to the requested permission using &xep0004;. The form SHOULD allow to fine tune the granted permissions. The server use a challenge which it MUST have generated himself.
</p>
<examplecaption='Server Asks User For The Permission'><![CDATA[
<p>The server SHOULD include a warning message, SHOULD translate the namespace to human friendly names (and MAY keep the original namespace in addition) and MUST set the default value to '<strong>none</strong>' (permission refused). The server SHOULD use namespace as field var, so a client can use it to have a customized display.</p>
<p>Here juliet accept that <em>priv.montaigu.net</em> use 'set' and 'get' to manage her roster, but doesn't want it to do any 'get' on her pubsub nodes.</p>
<p>Finaly, the server notify the entity of the permissions granted. For this it use a &QUERY; element with the 'allowed' type, and put the client jid in a 'from' attribute:</p>
<section2topic='Privileged Entity Send IQ Stanzas'anchor='priv_iq_client'>
<p>sending IQ stanza is done in the exact same way as for <linkurl='#priv_iq_admin'>admin mode</link>. If an entity want to sent a non authorized IQ, it get a &forbidden; error:</p>
<p>If a server or an entity supports the entity privilege protocol, it MUST report that fact by including a service discovery feature of "urn:xmpp:privilege:0" in response to a &xep0030; information request:</p>
<li>Server MAY keep permission granted to an entity by a client from one session to an other, but if it do so, it MUST provide a way to client to check already granted permission, and revoke them (possibly using &xep0050;).</li>
<li>If a client can't check or revoke permission (e.g. it doesn't support &xep0050;), the server MUST NOT keep granted permission from one session to an other, and permission will be asked on each new session.</li>
<li>If permissions are changed during a session, server MUST notify privileged entity of the new permissions, like in <linkurl='#client_perm'>permission request use case</link></li>
<li>Privileged entity nearly have the same possibility as the server itself, <em>admin</em> permission should be granted carefuly, only if you absolutely trust the entity.</li>
<li>A server MAY choose to filter allowed namespaces, to avoid giving dangerous permissions. In this case, it MUST always set the allowed type of filtered namespaces to <strong>none</strong></li>
<li>In case of filtering, a whitelist system is more secure and SHOULD be prefered to a blacklist (idealy, configuration would allow no filtering, whitelist filtering and blacklist filtering)</li>