From 0e05c2eb16fcb168300d61ececd9a4431d4d9331 Mon Sep 17 00:00:00 2001
From: Peter Saint-Andre <stpeter@jabber.org>
Date: Tue, 29 Sep 2009 23:38:06 +0000
Subject: [PATCH] added too-many-subscriptions error on subscribe

git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@3471 4b5297f7-1745-476d-ba37-a9c6900126ab
---
 xep-0060.xml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/xep-0060.xml b/xep-0060.xml
index 3f0ecd87..4f6db9e4 100644
--- a/xep-0060.xml
+++ b/xep-0060.xml
@@ -74,6 +74,7 @@
         <li>Removed subids from subscription approval forms because subscribers can have only one unapproved subscription request per node at a given time.</li>
         <li>Added optional support for delivery of notifications via XMPP IQ stanzas.</li>
         <li>Removed the notion of batch publishing because it makes information coherence and atom handling excessively difficult.</li>
+        <li>Added error handling for too-many-subscriptions to help prevent a certain denial of service attack.</li>
       </ul>
     </remark>
   </revision>
@@ -1181,6 +1182,7 @@ And by opposing end them?
         <li>The requesting entity is anonymous and the service does not allow anonymous entities to subscribe.</li>
         <li>The requesting entity has a pending subscription.</li>
         <li>The requesting entity is blocked from subscribing (e.g., because having an affiliation of outcast).</li>
+        <li>The requesting entity has attempted to establish too many subscriptions.</li>
         <li>The node does not support subscriptions.</li>
         <li>The node has moved.</li>
         <li>The node does not exist.</li>
@@ -1297,6 +1299,21 @@ And by opposing end them?
 </iq>
         ]]></example>
       </section4>
+      <section4 topic='Too Many Subscriptions' anchor='subscriber-subscribe-error-toomany'>
+        <p>If the requesting entity has attempted to establish too many subscriptions (where the definition of "too many" is a matter of local service policy), the service MUST return a &policy; error to the subscriber, specifying a pubsub-specific error condition of &lt;too-many-subscriptions/&gt;.</p>
+        <example caption='Requesting entity has exceeded limit on number of subscriptions'><![CDATA[
+<iq type='error'
+    from='pubsub.shakespeare.lit'
+    to='francisco@denmark.lit/barracks'
+    id='sub1'>
+  <error type='wait'>
+    <policy-violation xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
+    <too-many-subscriptions xmlns='http://jabber.org/protocol/pubsub#errors'/>
+  </error>
+</iq>
+        ]]></example>
+        <p>The service can match on bare JID or full JID in determining which subscribing entities match for the purpose of determining if an entity has requested too many subscriptions.</p>
+      </section4>
       <section4 topic='Subscriptions Not Supported' anchor='subscriber-subscribe-error-unsupported'>
         <p>If the node does not allow entities to subscribe, the service SHOULD return a &feature; error to the subscriber, specifying a pubsub-specific error condition of &lt;unsupported/&gt; and a feature of "subscribe".</p>
         <example caption='Subscribing not supported'><![CDATA[
@@ -6481,6 +6498,7 @@ xmpp:pubsub.shakespeare.lit?pubsub;action=retrieve;node=princely_musings
   <xs:element name='pending-subscription' type='empty'/>
   <xs:element name='presence-subscription-required' type='empty'/>
   <xs:element name='subid-required' type='empty'/>
+  <xs:element name='too-many-subscriptions' type='empty'/>
   <xs:element name='unsupported'>
     <xs:complexType>
       <xs:simpleContent>