[libvirt] [PATCH 3/3] virDomainNetFindIdx: Ignore auto generated MAC addresses

[Michal Privoznik]

When detaching an <interface/> from domain, it's MAC address is
parsed and if not present one is generated. If, however, no
corresponding interface is found in the domain, the following
error is reported:

error: operation failed: no device matching mac address 52:54:00:75:32:5b found

where the MAC address is the auto generated one. This might be
very confusing. Solution to this is to ignore auto generated MAC
address when looking up the device.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/conf/domain_conf.c | 45 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 87192eb2d..aab43d307 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -15634,11 +15634,17 @@ int virDomainNetInsert(virDomainDefPtr def, virDomainNetDefPtr net)
     return 0;
 }
 
-/* virDomainNetFindIdx: search according to mac address and guest side
- *                      PCI address (if specified)
+/**
+ * virDomainNetFindIdx:
+ * @def: domain definition
+ * @net: interface definition
  *
- * Return: index of match if unique match found
- *         -1 otherwise and an error is logged
+ * Lookup domain's network interface based on passed @net
+ * definition. If @net's MAC address was auto generated,
+ * the MAC comparison is ignored.
+ *
+ * Return: index of match if unique match found,
+ *         -1 otherwise and an error is logged.
  */
 int
 virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net)
@@ -15646,11 +15652,13 @@ virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net)
     size_t i;
     int matchidx = -1;
     char mac[VIR_MAC_STRING_BUFLEN];
+    bool MACAddrSpecified = !net->mac.generated;
     bool PCIAddrSpecified = virDomainDeviceAddressIsValid(&net->info,
                                                           VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI);
 
     for (i = 0; i < def->nnets; i++) {
-        if (virMacAddrCmp(&def->nets[i]->mac, &net->mac))
+        if (MACAddrSpecified &&
+            virMacAddrCmp(&def->nets[i]->mac, &net->mac) != 0)
             continue;
 
         if ((matchidx >= 0) && !PCIAddrSpecified) {
@@ -15660,9 +15668,15 @@ virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net)
              * specify only vendor and product ID, and there may be
              * multiples of those.
              */
-            virReportError(VIR_ERR_OPERATION_FAILED,
-                           _("multiple devices matching mac address %s found"),
-                           virMacAddrFormat(&net->mac, mac));
+            if (MACAddrSpecified) {
+                virReportError(VIR_ERR_OPERATION_FAILED,
+                               _("multiple devices matching mac address %s found"),
+                               virMacAddrFormat(&net->mac, mac));
+            } else {
+                virReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                               _("multiple matching devices found"));
+            }
+
             return -1;
         }
         if (PCIAddrSpecified) {
@@ -15679,8 +15693,9 @@ virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net)
             matchidx = i;
         }
     }
+
     if (matchidx < 0) {
-        if (PCIAddrSpecified) {
+        if (MACAddrSpecified && PCIAddrSpecified) {
             virReportError(VIR_ERR_OPERATION_FAILED,
                            _("no device matching mac address %s found on "
                              "%.4x:%.2x:%.2x.%.1x"),
@@ -15689,10 +15704,20 @@ virDomainNetFindIdx(virDomainDefPtr def, virDomainNetDefPtr net)
                            net->info.addr.pci.bus,
                            net->info.addr.pci.slot,
                            net->info.addr.pci.function);
-        } else {
+        } else if (PCIAddrSpecified) {
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("no device found on %.4x:%.2x:%.2x.%.1x"),
+                           net->info.addr.pci.domain,
+                           net->info.addr.pci.bus,
+                           net->info.addr.pci.slot,
+                           net->info.addr.pci.function);
+        } else if (MACAddrSpecified) {
             virReportError(VIR_ERR_OPERATION_FAILED,
                            _("no device matching mac address %s found"),
                            virMacAddrFormat(&net->mac, mac));
+        } else {
+            virReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                           _("no matching device found"));
         }
     }
     return matchidx;
-- 
2.13.5