network: get vlan info for Open vSwitch interfaces from proper source

This bug was revealed by the crash described in

  https://bugzilla.redhat.com/show_bug.cgi?id=852383

The vlan info pointer sent to virNetDevOpenvswitchAddPort should never
be non-NULL unless there is at least one tag. The factthat such a vlan
info pointer was receveid pointed out that a caller was passing the
wrong pointer. Instead of sending &net->vlan, the result of
virDomainNetGetActualVlan(net) should be sent - that function will
look for vlan info in net->data.network.actual->vlan, and in cany case
return NULL instead of a pointer if the vlan info it finds has no
tags.

Aside from causing the crash, sending a hardcoded &net->vlan has the
effect of ignoring vlan info from a <network> or <portgroup> config.

src/lxc/lxc_process.c

@@ -325,7 +325,7 @@ static int virLXCProcessSetupInterfaceBridged(virConnectPtr conn,
 
     if (vport && vport->virtPortType == VIR_NETDEV_VPORT_PROFILE_OPENVSWITCH)
         ret = virNetDevOpenvswitchAddPort(brname, parentVeth, &net->mac,
-                                          vm->uuid, vport, &net->vlan);
+                                          vm->uuid, vport, virDomainNetGetActualVlan(net));
     else
         ret = virNetDevBridgeAddPort(brname, parentVeth);
     if (ret < 0)

src/qemu/qemu_command.c

@@ -258,7 +258,7 @@ qemuNetworkIfaceConnect(virDomainDefPtr def,
     err = virNetDevTapCreateInBridgePort(brname, &net->ifname, &net->mac,
                                          def->uuid, &tapfd,
                                          virDomainNetGetActualVirtPortProfile(net),
-                                         &net->vlan,
+                                         virDomainNetGetActualVlan(net),
                                          tap_create_flags);
     virDomainAuditNetDevice(def, net, "/dev/net/tun", tapfd >= 0);
     if (err < 0) {

src/uml/uml_conf.c

@@ -141,7 +141,7 @@ umlConnectTapDevice(virConnectPtr conn,
     if (virNetDevTapCreateInBridgePort(bridge, &net->ifname, &net->mac,
                                        vm->uuid, NULL,
                                        virDomainNetGetActualVirtPortProfile(net),
-                                       &net->vlan,
+                                       virDomainNetGetActualVlan(net),
                                        VIR_NETDEV_TAP_CREATE_IFUP) < 0) {
         if (template_ifname)
             VIR_FREE(net->ifname);