conf: Don't try formating non-existing addresses

Commit a6f9af82 added checking for address colisions between
starting and ending addresses of forwarding addresses, but forgot that
there might be no addresses set at all.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/conf/network_conf.c

@@ -1731,9 +1731,26 @@ virNetworkForwardNatDefParseXML(const char *networkName,
         goto cleanup;
     }
 
-    /* verify that start <= end */
-    if (virSocketAddrGetRange(&def->addr.start, &def->addr.end, NULL, 0) < 0)
-        goto cleanup;
+    if (addrStart && addrEnd) {
+        /* verify that start <= end */
+        if (virSocketAddrGetRange(&def->addr.start, &def->addr.end, NULL, 0) < 0)
+            goto cleanup;
+    } else {
+        if (addrStart) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Only start address '%s' specified in <nat> in "
+                             "<forward> in network '%s'"),
+                           addrStart, networkName);
+            goto cleanup;
+        }
+        if (addrEnd) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Only end address '%s' specified in <nat> in "
+                             "<forward> in network '%s'"),
+                           addrEnd, networkName);
+            goto cleanup;
+        }
+    }
 
     /* ports for SNAT and MASQUERADE */
     nNatPorts = virXPathNodeSet("./port", ctxt, &natPortNodes);

tests/networkxml2xmlin/nat-network-forward-nat-no-address.xml

+<network>
+  <name>default</name>
+  <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9b</uuid>
+  <bridge name="virbr0"/>
+  <forward mode="nat" dev="eth1">
+    <nat>
+      <port start='60000' end='65432'/>
+    </nat>
+  </forward>
+  <ip address="192.168.122.1" netmask="255.255.255.0">
+    <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">
+  </ip>
+  <ip family="ipv6" address="2001:db8:ac10:fe01::1" prefix="64">
+  </ip>
+  <ip family="ipv6" address="2001:db8:ac10:fd01::1" prefix="64">
+  </ip>
+  <ip family="ipv4" address="10.24.10.1">
+  </ip>
+</network>

tests/networkxml2xmlout/nat-network-forward-nat-no-address.xml

+<network>
+  <name>default</name>
+  <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9b</uuid>
+  <forward dev='eth1' mode='nat'>
+    <nat>
+      <port start='60000' end='65432'/>
+    </nat>
+    <interface dev='eth1'/>
+  </forward>
+  <bridge name='virbr0' stp='on' delay='0'/>
+  <ip address='192.168.122.1' netmask='255.255.255.0'>
+    <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'>
+  </ip>
+  <ip family='ipv6' address='2001:db8:ac10:fe01::1' prefix='64'>
+  </ip>
+  <ip family='ipv6' address='2001:db8:ac10:fd01::1' prefix='64'>
+  </ip>
+  <ip family='ipv4' address='10.24.10.1'>
+  </ip>
+</network>

tests/networkxml2xmltest.c

@@ -99,6 +99,7 @@ mymain(void)
     DO_TEST("nat-network-dns-forward-plain");
     DO_TEST("nat-network-dns-forwarders");
     DO_TEST("nat-network-forward-nat-address");
+    DO_TEST("nat-network-forward-nat-no-address");
     DO_TEST("8021Qbh-net");
     DO_TEST("direct-net");
     DO_TEST("host-bridge-net");