network: Add support for local PTR domains

Similarly to localOnly DNS domain, localPtr attribute can be used to
tell the DNS server not to forward reverse lookups for unknown IPs which
belong to the virtual network.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

docs/formatnetwork.html.in

@@ -855,14 +855,14 @@
     <hostname>myhostalias</hostname>
   </host>
 </dns>
-<ip address="192.168.122.1" netmask="255.255.255.0">
+<ip address="192.168.122.1" netmask="255.255.255.0" localPtr="yes">
   <dhcp>
     <range start="192.168.122.100" end="192.168.122.254"/>
     <host mac="00:16:3e:77:e2:ed" name="foo.example.com" ip="192.168.122.10"/>
     <host mac="00:16:3e:3e:a9:1a" name="bar.example.com" ip="192.168.122.11"/>
   </dhcp>
 </ip>
-<ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64"/>
+<ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64" localPtr="yes"/>
 <route family="ipv6" address="2001:db9:ca1:1::" prefix="64" gateway="2001:db8:ca2:2::2"/>
 </pre>
 
@@ -983,11 +983,18 @@
         to specify the type of address &mdash; <code>ipv4</code> or
         <code>ipv6</code>; if no <code>family</code> is given,
         <code>ipv4</code> is assumed. More than one address of each family can
-        be defined for a network. The <code>ip</code> element is supported
-        <span class="since">since 0.3.0</span>. IPv6, multiple addresses on a
-        single network, <code>family</code>, and <code>prefix</code> are
-        supported <span class="since">since 0.8.7</span>. The <code>ip</code>
-        element may contain the following elements:
+        be defined for a network. The optional <code>localPtr</code> attribute
+        (<span class="since">since 3.0.0</span>) configures the DNS server to
+        not forward any reverse DNS requests for IP addresses from the network
+        configured by the <code>address</code> and
+        <code>netmask</code>/<code>prefix</code> attributes. For some unusual
+        network prefixes (not divisible by 8 for IPv4 or not divisible by 4 for
+        IPv6) libvirt may be unable to compute the PTR domain automatically.
+        The <code>ip</code> element is supported <span class="since">since
+        0.3.0</span>. IPv6, multiple addresses on a single network,
+        <code>family</code>, and <code>prefix</code> are supported
+        <span class="since">since 0.8.7</span>. The <code>ip</code> element may
+        contain the following elements:
 
         <dl>
           <dt><code>tftp</code></dt>

docs/news.html.in

@@ -16,6 +16,8 @@
     <ul>
       <li><strong>New features</strong>
         <ul>
+          <li>New localPtr attribute for "ip" element in network XML
+          </li>
           <li>qemu: Support QEMU group I/O throttling<br/>
           Add the capability to allow group I/O throttling via a new
           domain &lt;disk&gt; &lt;iotune&gt; subelement "group_name"

docs/schemas/network.rng

@@ -339,6 +339,9 @@
             <optional>
               <attribute name="family"><ref name="addr-family"/></attribute>
             </optional>
+            <optional>
+              <attribute name="localPtr"><ref name="virYesNo"/></attribute>
+            </optional>
             <interleave>
               <optional>
                 <element name="tftp">