[RFC PATCH] network: add an option to disable dnsmasq's bind-dynamic

[Cédric Bosdonnat <cbosdonnat@xxxxxxxx>]

When building vlans on top of veth networks, dnsmasq doesn't catch
DNS requests on the vlans interfaces. Allowing to disable the
bind-dynamic helps this use case.
---

 src/conf/network_conf.c     | 12 ++++++++++++
 src/conf/network_conf.h     |  1 +
 src/network/bridge_driver.c |  3 ++-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
index f4a9df0..63e26e1 100644
--- a/src/conf/network_conf.c
+++ b/src/conf/network_conf.c
@@ -1987,6 +1987,7 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
     xmlNodePtr forwardNode = NULL;
     char *ipv6nogwStr = NULL;
     char *trustGuestRxFilters = NULL;
+    char *binddynamicStr = NULL;
     xmlNodePtr save = ctxt->node;
     xmlNodePtr bandwidthNode = NULL;
     xmlNodePtr vlanNode;
@@ -2049,6 +2050,16 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
         VIR_FREE(trustGuestRxFilters);
     }
 
+    /* Default for binddynamic is on */
+    def->binddynamic = true;
+    binddynamicStr = virXPathString("string(./@binddynamic)", ctxt);
+    if (binddynamicStr) {
+        if (STRNEQ(binddynamicStr, "no")) {
+            def->binddynamic = false;
+        }
+        VIR_FREE(binddynamicStr);
+    }
+
     /* Parse network domain information */
     def->domain = virXPathString("string(./domain[1]/@name)", ctxt);
     tmp = virXPathString("string(./domain[1]/@localOnly)", ctxt);
@@ -2326,6 +2337,7 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
     VIR_FREE(ipNodes);
     VIR_FREE(portGroupNodes);
     VIR_FREE(ipv6nogwStr);
+    VIR_FREE(binddynamicStr);
     VIR_FREE(trustGuestRxFilters);
     ctxt->node = save;
     return NULL;
diff --git a/src/conf/network_conf.h b/src/conf/network_conf.h
index f69d999..163581e 100644
--- a/src/conf/network_conf.h
+++ b/src/conf/network_conf.h
@@ -253,6 +253,7 @@ struct _virNetworkDef {
     virNetDevBandwidthPtr bandwidth;
     virNetDevVlan vlan;
     int trustGuestRxFilters; /* enum virTristateBool */
+    bool binddynamic; /* to force off bind_dynamic option of dnsmasq */
 };
 
 typedef struct _virNetworkObj virNetworkObj;
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index d195085..5dddc4b 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -988,7 +988,8 @@ networkDnsmasqConfContents(virNetworkObjPtr network,
     /* dnsmasq will *always* listen on localhost unless told otherwise */
     virBufferAddLit(&configbuf, "except-interface=lo\n");
 
-    if (dnsmasqCapsGet(caps, DNSMASQ_CAPS_BIND_DYNAMIC)) {
+    if (network->def->binddynamic &&
+        dnsmasqCapsGet(caps, DNSMASQ_CAPS_BIND_DYNAMIC)) {
         /* using --bind-dynamic with only --interface (no
          * --listen-address) prevents dnsmasq from responding to dns
          * queries that arrive on some interface other than our bridge
-- 
2.1.4

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