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0.5

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Peter Saint-Andre 2013-08-28 09:28:26 -06:00
parent 29d75cb32b
commit 932ef25a87
1 changed files with 64 additions and 6 deletions
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xep-0297.xml
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@ -23,6 +23,17 @@
<schemaloc/>
&mwild;
&ksmith;
&stpeter;
<revision>
<version>0.5</version>
<date>2013-06-05</date>
<initials>mw</initials>
<remark>
<p>Incorporated Last Call feedback, including; clarify that client handling of non-message stanzas,
add a disco feature, remove references to deferred XEPs, tighten up the schema to allow only stanzas
to be forwarded.</p>
</remark>
</revision>
<revision>
<version>0.4</version>
<date>2012-07-05</date>
@ -67,7 +78,7 @@
<p>Several properties are desirable when forwarding stanzas:</p>
<ul>
<li>The original sender and receiver should be identified.</li>
<li>Extension payloads should be included (not only a message &lt;body/&gt;</li>
<li>Most extension payloads should be included (not only a message &lt;body/&gt;).</li>
<li>It should be possible to annotate the stanza (e.g. with a timestamp) without ambiguity as to the original stanza contents.</li>
<li>It should allow features such as encryption or signing of the original stanza to survive the forwarding.</li>
</ul>
@ -132,13 +143,44 @@
</ol>
</section2>
</section1>
<section1 topic="Determining Support" anchor="support">
<p>Clients that implement this specification to display simple forwarded messages (i.e. those not part of another extension)
SHOULD indicate their support via the 'urn:xmpp:forward:0' feature.</p>
<example caption='Client requests features of a contact'><![CDATA[
<iq xmlns='jabber:client'
type='get'
from='romeo@montague.lit/orchard'
to='juliet@capulet.lit/balcony'
id='info1'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>]]></example>
<example caption='Contact responds with forwarding feature'><![CDATA[
<iq xmlns='jabber:client'
type='result'
to='romeo@montague.net/orchard'
from='juliet@capulet.lit/balcony'
id='info1'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='urn:xmpp:forward:0'/>
...
</query>
</iq>]]></example>
<p>Senders SHOULD NOT forward messages using this protocol to recipients that have not indicated support for it. However they may still
format the forward as plain text inside the &lt;body&gt; of a standard message stanza for compatibility with clients lacking support.
Such a plain text version SHOULD NOT be included in a stanza using this extension (e.g. as a 'fallback'), as receiving entities are
expected to display the &lt;body&gt; of a message as well as any forwarded stanza therein.
</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
<p>Forwarding stanzas can reveal information about the original sender, including possible presence leaks as well as the stanza payloads themselves. Any extensions using this format must therefore consider the implications of this.</p>
<p>Forwarding can either be used as-is, or in the context of another specification, with different security considerations as described below.</p>
<section2 topic='As-is' anchor='as-is-sc'>
<p>Receipt of a forwarded stanza from a third-party does not guarantee that the original stanza was actually received, or that the content has not been modified, by the forwarder. Integrity of the original stanza can only be determined through digital signing mechanisms such as described in &xep0285; and &xep0290;.</p>
<p>Receipt of a forwarded stanza from a third-party does not guarantee that the original stanza was actually received, or that the content has not been modified, by the forwarder. Integrity of the original stanza can only be determined through cryptographic signatures for example, which are beyond the scope of this specification.</p>
<p>Considering the above an end-user client should take special care in its rendering of forwarded stanzas, such as forwarded messages, to ensure that the user cannot mistake it for a message received directly from the original sender.</p>
<p>An entity SHOULD NOT trust that forwards are genuine when receiving them unprovoked (i.e. outside the scope of another specification).</p>
<p>Forwarded stanzas MUST NOT be processed as if they were non-forwarded stanzas. Furthermore a client SHOULD ignore non-&lt;message&gt;
stanzas that are not embedded within another extension.</p>
</section2>
<section2 topic='Extensions' anchor='extensions-sc'>
<p>While security considerations are ultimately dependent upon the specifications using the format defined herein, forwarding introduces scope for stanza forgery such that authors of derivative specifications will need to address security considerations themselves. These need to cover which entities a client should accept forwards from, and which entities those are permitted to forward stanzas for. For example, a specification may choose to only trust forwards if they are received from the user's client, another client on the bare JID, or the user's server.</p>
@ -154,19 +196,35 @@
xmlns='urn:xmpp:forward:0'
elementFormDefault='qualified'>
<xs:import namespace='jabber:client'/>
<xs:import namespace='jabber:server'/>
<xs:element name='forwarded'>
<xs:complexType>
<xs:sequence xmlns:delay='urn:xmpp:delay'>
<xs:sequence xmlns:delay='urn:xmpp:delay'
xmlns:client='jabber:client'
xmlns:server='jabber:server'>
<xs:element ref='delay:delay' minOccurs='0' maxOccurs='1' />
<xs:any namespace='##other' minOccurs='1' maxOccurs='1' />
<xs:choice minOccurs='0' maxOccurs='1'>
<xs:choice>
<xs:element ref='client:message'/>
<xs:element ref='client:presence'/>
<xs:element ref='client:iq'/>
</xs:choice>
<xs:choice>
<xs:element ref='server:message'/>
<xs:element ref='server:presence'/>
<xs:element ref='server:iq'/>
</xs:choice>
</xs:choice>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
]]></code>
</section1>
<section1 topic='Acknowledgements' anchor='ack'>
<p>Thanks to Matt Miller and Florian Zeitz for feedback.</p>
<p>Thanks to Matt Miller, Florian Zeitz, Jefry Lagrange, Kim Alvefur and Kurt Zeilenga for their feedback.</p>
</section1>
</xep>