network: don't add "no-resolv" if we still need DNS servers from resolv.conf

It was pointed out here:

  https://bugzilla.redhat.com/show_bug.cgi?id=1331796#c4

that we shouldn't be adding a "no-resolv" to the dnsmasq.conf file for
a network if there isn't any <forwarder> element that specifies an IP
address but no qualifying domain. If there is such an element, it will
handle all DNS requests that weren't otherwise handled by one of the
forwarder entries with a matching domain attribute. If not, then DNS
requests that don't match the domain of any <forwarder> would not be
resolved if we added no-resolv.

So, only add "no-resolv" when there is at least one <forwarder>
element that specifies an IP address but no qualifying domain.

diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index c5ec2823d319845d1f00ddfcd80a5027c9a4ee95..32c5ab7a71889953a26c6aea8e167ec1fc9f05c9 100644 (file)
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -1085,7 +1085,15 @@ networkDnsmasqConfContents(virNetworkObjPtr network,
         virBufferAddLit(&configbuf, "port=0\n");
 
     if (wantDNS && network->def->dns.forwarders) {
-        virBufferAddLit(&configbuf, "no-resolv\n");
+        /* addNoResolv should be set to true if there are any entries
+         * that specify an IP address for requests, but no domain
+         * qualifier (implying that all requests otherwise "unclaimed"
+         * should be sent to that address). if it is still false when
+         * we've looked at all entries, it means we still need the
+         * host's resolv.conf for some cases.
+         */
+        bool addNoResolv = false;
+
         for (i = 0; i < network->def->dns.nfwds; i++) {
             virNetworkDNSForwarderPtr fwd = &network->def->dns.forwarders[i];
 
@@ -1099,11 +1107,15 @@ networkDnsmasqConfContents(virNetworkObjPtr network,
                     goto cleanup;
                 virBufferAsprintf(&configbuf, "%s\n", addr);
                 VIR_FREE(addr);
+                if (!fwd->domain)
+                    addNoResolv = true;
             } else {
                 /* "don't forward requests for this domain" */
                 virBufferAddLit(&configbuf, "#\n");
             }
         }
+        if (addNoResolv)
+            virBufferAddLit(&configbuf, "no-resolv\n");
     }
 
     if (network->def->domain) {

diff --git a/tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.conf b/tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.conf
new file mode 100644 (file)
index 0000000..52d000a
--- /dev/null
+++ b/tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.conf
@@ -0,0 +1,12 @@
+##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
+server=/example.com/192.168.1.1
+except-interface=lo
+bind-dynamic
+interface=virbr0
+addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts

diff --git a/tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.xml b/tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.xml
new file mode 100644 (file)
index 0000000..9661ce5
--- /dev/null
+++ b/tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.xml
@@ -0,0 +1,11 @@
+<network>
+  <name>default</name>
+  <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9c</uuid>
+  <forward mode='nat'/>
+  <bridge name='virbr0' stp='on' delay='0'/>
+  <dns>
+    <forwarder domain='example.com' addr='192.168.1.1'/>
+  </dns>
+  <ip address='192.168.122.1' netmask='255.255.255.0'>
+  </ip>
+</network>

diff --git a/tests/networkxml2confdata/nat-network-dns-forwarders.conf b/tests/networkxml2confdata/nat-network-dns-forwarders.conf
index 0bd76bf60c9701a52a4c8502fd79ccb74af2fa7c..1b0c94c3fba609b2fad9205800979b6592926474 100644 (file)
--- a/tests/networkxml2confdata/nat-network-dns-forwarders.conf
+++ b/tests/networkxml2confdata/nat-network-dns-forwarders.conf
@@ -5,11 +5,11 @@
 ##
 ## dnsmasq conf file created by libvirt
 strict-order
-no-resolv
 server=8.8.8.8
 server=8.8.4.4
 server=/example.com/192.168.1.1
 server=/www.example.com/#
+no-resolv
 except-interface=lo
 bind-dynamic
 interface=virbr0

diff --git a/tests/networkxml2conftest.c b/tests/networkxml2conftest.c
index 9b6107707cefd6279394c612228d0ac968707adf..e2522fccd7666acf8159455d5df4dd0a0e4c7c2e 100644 (file)
--- a/tests/networkxml2conftest.c
+++ b/tests/networkxml2conftest.c
@@ -137,6 +137,7 @@ mymain(void)
     DO_TEST("nat-network-dns-hosts", full);
     DO_TEST("nat-network-dns-forward-plain", full);
     DO_TEST("nat-network-dns-forwarders", full);
+    DO_TEST("nat-network-dns-forwarder-no-resolv", full);
     DO_TEST("nat-network-dns-local-domain", full);
     DO_TEST("dhcp6-network", dhcpv6);
     DO_TEST("dhcp6-nat-network", dhcpv6);

diff --git a/tests/networkxml2xmlin/nat-network-dns-forwarder-no-resolv.xml b/tests/networkxml2xmlin/nat-network-dns-forwarder-no-resolv.xml
new file mode 100644 (file)
index 0000000..9661ce5
--- /dev/null
+++ b/tests/networkxml2xmlin/nat-network-dns-forwarder-no-resolv.xml
@@ -0,0 +1,11 @@
+<network>
+  <name>default</name>
+  <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9c</uuid>
+  <forward mode='nat'/>
+  <bridge name='virbr0' stp='on' delay='0'/>
+  <dns>
+    <forwarder domain='example.com' addr='192.168.1.1'/>
+  </dns>
+  <ip address='192.168.122.1' netmask='255.255.255.0'>
+  </ip>
+</network>

diff --git a/tests/networkxml2xmlout/nat-network-dns-forwarder-no-resolv.xml b/tests/networkxml2xmlout/nat-network-dns-forwarder-no-resolv.xml
new file mode 100644 (file)
index 0000000..9661ce5
--- /dev/null
+++ b/tests/networkxml2xmlout/nat-network-dns-forwarder-no-resolv.xml
@@ -0,0 +1,11 @@
+<network>
+  <name>default</name>
+  <uuid>81ff0d90-c91e-6742-64da-4a736edb9a9c</uuid>
+  <forward mode='nat'/>
+  <bridge name='virbr0' stp='on' delay='0'/>
+  <dns>
+    <forwarder domain='example.com' addr='192.168.1.1'/>
+  </dns>
+  <ip address='192.168.122.1' netmask='255.255.255.0'>
+  </ip>
+</network>

diff --git a/tests/networkxml2xmltest.c b/tests/networkxml2xmltest.c
index cfaf7181aaa934fcffa55b7c6829a0e47f700b4a..effd85ad054bed5d4b33127d303a286edb41b68a 100644 (file)
--- a/tests/networkxml2xmltest.c
+++ b/tests/networkxml2xmltest.c
@@ -141,6 +141,7 @@ mymain(void)
     DO_TEST("nat-network-dns-hosts");
     DO_TEST("nat-network-dns-forward-plain");
     DO_TEST("nat-network-dns-forwarders");
+    DO_TEST("nat-network-dns-forwarder-no-resolv");
     DO_TEST("nat-network-forward-nat-address");
     DO_TEST("nat-network-forward-nat-no-address");
     DO_TEST("8021Qbh-net");