[libvirt] [PATCH] network: don't add "no-resolv" if we still need DNS servers from resolv.conf
Laine Stump
laine at laine.org
Fri Mar 17 16:33:14 UTC 2017
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.
---
src/network/bridge_driver.c | 14 +++++++++++++-
.../nat-network-dns-forwarder-no-resolv.conf | 12 ++++++++++++
.../nat-network-dns-forwarder-no-resolv.xml | 11 +++++++++++
tests/networkxml2confdata/nat-network-dns-forwarders.conf | 2 +-
tests/networkxml2conftest.c | 1 +
.../nat-network-dns-forwarder-no-resolv.xml | 11 +++++++++++
.../nat-network-dns-forwarder-no-resolv.xml | 11 +++++++++++
tests/networkxml2xmltest.c | 1 +
8 files changed, 61 insertions(+), 2 deletions(-)
create mode 100644 tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.conf
create mode 100644 tests/networkxml2confdata/nat-network-dns-forwarder-no-resolv.xml
create mode 100644 tests/networkxml2xmlin/nat-network-dns-forwarder-no-resolv.xml
create mode 100644 tests/networkxml2xmlout/nat-network-dns-forwarder-no-resolv.xml
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index c5ec282..32c5ab7 100644
--- 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
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
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 0bd76bf..1b0c94c 100644
--- 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 9b61077..e2522fc 100644
--- 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
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
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 cfaf718..effd85a 100644
--- 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");
--
2.9.3
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