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: NJiri 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">

src/conf/network_conf.c

@@ -1507,6 +1507,7 @@ virNetworkIPDefParseXML(const char *networkName,
     unsigned long prefix = 0;
     int prefixRc;
     int result = -1;
+    char *localPtr = NULL;
 
     save = ctxt->node;
     ctxt->node = node;
@@ -1549,6 +1550,17 @@ virNetworkIPDefParseXML(const char *networkName,
     else
         def->prefix = prefix;
 
+    localPtr = virXPathString("string(./@localPtr)", ctxt);
+    if (localPtr) {
+        def->localPTR = virTristateBoolTypeFromString(localPtr);
+        if (def->localPTR <= 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Invalid localPtr value '%s' in network '%s'"),
+                           localPtr, networkName);
+            goto cleanup;
+        }
+    }
+
     /* validate address, etc. for each family */
     if ((def->family == NULL) || (STREQ(def->family, "ipv4"))) {
         if (!(VIR_SOCKET_ADDR_IS_FAMILY(&def->address, AF_INET) ||
@@ -1627,6 +1639,7 @@ virNetworkIPDefParseXML(const char *networkName,
         virNetworkIPDefClear(def);
     VIR_FREE(address);
     VIR_FREE(netmask);
+    VIR_FREE(localPtr);
 
     ctxt->node = save;
     return result;
@@ -2652,6 +2665,12 @@ virNetworkIPDefFormat(virBufferPtr buf,
     }
     if (def->prefix > 0)
         virBufferAsprintf(buf, " prefix='%u'", def->prefix);
+
+    if (def->localPTR) {
+        virBufferAsprintf(buf, " localPtr='%s'",
+                          virTristateBoolTypeToString(def->localPTR));
+    }
+
     virBufferAddLit(buf, ">\n");
     virBufferAdjustIndent(buf, 2);
 

src/conf/network_conf.h

@@ -162,6 +162,8 @@ struct _virNetworkIPDef {
     unsigned int prefix;        /* ipv6 - only prefix allowed */
     virSocketAddr netmask;      /* ipv4 - either netmask or prefix specified */
 
+    int localPTR; /* virTristateBool */
+
     size_t nranges;             /* Zero or more dhcp ranges */
     virSocketAddrRangePtr ranges;
 

src/network/bridge_driver.c

@@ -994,6 +994,43 @@ networkBuildDnsmasqHostsList(dnsmasqContext *dctx,
 }
 
 
+static int
+networkDnsmasqConfLocalPTRs(virBufferPtr buf,
+                            virNetworkDefPtr def)
+{
+    virNetworkIPDefPtr ip;
+    size_t i;
+    char *ptr = NULL;
+    int rc;
+
+    for (i = 0; i < def->nips; i++) {
+        ip = def->ips + i;
+
+        if (ip->localPTR != VIR_TRISTATE_BOOL_YES)
+            continue;
+
+        if ((rc = virSocketAddrPTRDomain(&ip->address,
+                                         virNetworkIPDefPrefix(ip),
+                                         &ptr)) < 0) {
+            if (rc == -2) {
+                int family = VIR_SOCKET_ADDR_FAMILY(&ip->address);
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("PTR domain for %s network with prefix %u "
+                                 "cannot be automatically created"),
+                               (family == AF_INET) ? "IPv4" : "IPv6",
+                               virNetworkIPDefPrefix(ip));
+            }
+            return -1;
+        }
+
+        virBufferAsprintf(buf, "local=/%s/\n", ptr);
+        VIR_FREE(ptr);
+    }
+
+    return 0;
+}
+
+
 int
 networkDnsmasqConfContents(virNetworkObjPtr network,
                            const char *pidfile,
@@ -1079,6 +1116,10 @@ networkDnsmasqConfContents(virNetworkObjPtr network,
                           network->def->domain);
     }
 
+    if (wantDNS &&
+        networkDnsmasqConfLocalPTRs(&configbuf, network->def) < 0)
+        goto cleanup;
+
     if (wantDNS && network->def->dns.forwardPlainNames == VIR_TRISTATE_BOOL_NO) {
         virBufferAddLit(&configbuf, "domain-needed\n");
         /* need to specify local=// whether or not a domain is

tests/networkxml2confdata/ptr-domains-auto.conf

+##WARNING:  THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
+##OVERWRITTEN AND LOST.  Changes to this configuration should be made using:
+##    virsh net-edit default
+## or other application using the libvirt API.
+##
+## dnsmasq conf file created by libvirt
+strict-order
+local=/122.168.192.in-addr.arpa/
+local=/1.0.e.f.0.1.c.a.8.b.d.0.1.0.0.2.ip6.arpa/
+except-interface=lo
+bind-dynamic
+interface=virbr0
+dhcp-range=192.168.122.2,192.168.122.254
+dhcp-no-override
+dhcp-authoritative
+dhcp-lease-max=253
+dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile
+addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts
+dhcp-range=2001:db8:ac10:fe01::1,ra-only
+dhcp-range=2001:db8:ac10:fd01::1,ra-only

tests/networkxml2confdata/ptr-domains-auto.xml

+<network>
+  <name>default</name>
+  <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9b</uuid>
+  <forward dev='eth1' mode='nat'/>
+  <bridge name='virbr0' stp='on' delay='0'/>
+  <ip address='192.168.122.1' netmask='255.255.255.0' localPtr='yes'>
+    <dhcp>
+      <range start='192.168.122.2' end='192.168.122.254'/>
+      <host mac='00:16:3e:77:e2:ed' name='a.example.com' ip='192.168.122.10'/>
+      <host mac='00:16:3e:3e:a9:1a' name='b.example.com' ip='192.168.122.11'/>
+    </dhcp>
+  </ip>
+  <ip family='ipv4' address='192.168.123.1' netmask='255.255.255.0' localPtr='no'>
+  </ip>
+  <ip family='ipv6' address='2001:db8:ac10:fe01::1' prefix='64' localPtr='yes'>
+  </ip>
+  <ip family='ipv6' address='2001:db8:ac10:fd01::1' prefix='64'>
+  </ip>
+  <ip family='ipv4' address='10.24.10.1'>
+  </ip>
+</network>

tests/networkxml2conftest.c

@@ -129,6 +129,7 @@ mymain(void)
     DO_TEST("dhcp6-network", dhcpv6);
     DO_TEST("dhcp6-nat-network", dhcpv6);
     DO_TEST("dhcp6host-routed-network", dhcpv6);
+    DO_TEST("ptr-domains-auto", dhcpv6);
 
     virObjectUnref(dhcpv6);
     virObjectUnref(full);