[libvirt] [PATCH v2 2/2] nwfilter: Check for filter presence before open connect during teardown

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=1608275

Instantiation of an nwfilter binding is only allowed when
the net->filter is defined for the network; however, the
teardown of the binding does not make this check. This
leaves open the possibility that the teardown could be
called during guest shutdown/teardown in session mode
resulting in the following error being logged:

    error : nwfilterConnectOpen:383 : internal error: unexpected
    nwfilter URI path '/session', try nwfilter:///system

So before going through the teardown processing, let's
be sure the network had a filter and then attempt to
get a connection. For session mode it's not even possible
create an nwfilter binding.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/conf/domain_nwfilter.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/conf/domain_nwfilter.c b/src/conf/domain_nwfilter.c
index f39c8a1f9b..e75fb598e8 100644
--- a/src/conf/domain_nwfilter.c
+++ b/src/conf/domain_nwfilter.c
@@ -149,9 +149,12 @@ virDomainConfNWFilterTeardownImpl(virConnectPtr conn,
 void
 virDomainConfNWFilterTeardown(virDomainNetDefPtr net)
 {
-    virConnectPtr conn = virGetConnectNWFilter();
+    virConnectPtr conn;
 
-    if (!conn)
+    if (!net->filter)
+        return;
+
+    if (!(conn = virGetConnectNWFilter()))
         return;
 
     virDomainConfNWFilterTeardownImpl(conn, net);
@@ -163,14 +166,19 @@ void
 virDomainConfVMNWFilterTeardown(virDomainObjPtr vm)
 {
     size_t i;
-    virConnectPtr conn = virGetConnectNWFilter();
+    virConnectPtr conn = NULL;
 
-    if (!conn)
-        return;
+    for (i = 0; i < vm->def->nnets; i++) {
+        virDomainNetDefPtr net = vm->def->nets[i];
 
+        if (!net->filter)
+            continue;
 
-    for (i = 0; i < vm->def->nnets; i++)
-        virDomainConfNWFilterTeardownImpl(conn, vm->def->nets[i]);
+        if (!conn && !(conn = virGetConnectNWFilter()))
+            return;
+
+        virDomainConfNWFilterTeardownImpl(conn, net);
+    }
 
     virObjectUnref(conn);
 }
-- 
2.17.1