network: don't allow multiple default portgroups

This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=868483

virNetworkUpdate, virNetworkDefine, and virNetworkCreate all three
allow network definitions to contain multiple <portgroup> elements
with default='yes'. Only a single default portgroup should be allowed
for each network.

This patch updates networkValidate() (called by both
virNetworkCreate() and virNetworkDefine()) and
virNetworkDefUpdatePortGroup (called by virNetworkUpdate() to not
allow multiple default portgroups.

src/conf/network_conf.c

@@ -2752,7 +2752,8 @@ virNetworkDefUpdatePortGroup(virNetworkDefPtr def,
                              /* virNetworkUpdateFlags */
                              unsigned int fflags ATTRIBUTE_UNUSED)
 {
-    int ii, ret = -1;
+    int ii, foundName = -1, foundDefault = -1;
+    int ret = -1;
     virPortGroupDef portgroup;
 
     memset(&portgroup, 0, sizeof(portgroup));
@@ -2766,9 +2767,11 @@ virNetworkDefUpdatePortGroup(virNetworkDefPtr def,
     /* check if a portgroup with same name already exists */
     for (ii = 0; ii < def->nPortGroups; ii++) {
         if (STREQ(portgroup.name, def->portGroups[ii].name))
-            break;
+            foundName = ii;
+        if (def->portGroups[ii].isDefault)
+            foundDefault = ii;
     }
-    if (ii == def->nPortGroups &&
+    if (foundName == -1 &&
         ((command == VIR_NETWORK_UPDATE_COMMAND_MODIFY) ||
          (command == VIR_NETWORK_UPDATE_COMMAND_DELETE))) {
         virReportError(VIR_ERR_OPERATION_INVALID,
@@ -2776,7 +2779,7 @@ virNetworkDefUpdatePortGroup(virNetworkDefPtr def,
                          "in network '%s' matching <portgroup name='%s'>"),
                        def->name, portgroup.name);
         goto cleanup;
-    } else if (ii < def->nPortGroups &&
+    } else if (foundName >= 0 &&
                ((command == VIR_NETWORK_UPDATE_COMMAND_ADD_FIRST) ||
                 (command == VIR_NETWORK_UPDATE_COMMAND_ADD_LAST))) {
         virReportError(VIR_ERR_OPERATION_INVALID,
@@ -2787,11 +2790,25 @@ virNetworkDefUpdatePortGroup(virNetworkDefPtr def,
         goto cleanup;
     }
 
+    /* if there is already a different default, we can't make this
+     * one the default.
+     */
+    if (command != VIR_NETWORK_UPDATE_COMMAND_DELETE &&
+        portgroup.isDefault &&
+        foundDefault >= 0 && foundDefault != foundName) {
+        virReportError(VIR_ERR_OPERATION_INVALID,
+                       _("a different portgroup entry in "
+                         "network '%s' is already set as the default. "
+                         "Only one default is allowed."),
+                       def->name);
+        goto cleanup;
+    }
+
     if (command == VIR_NETWORK_UPDATE_COMMAND_MODIFY) {
 
         /* replace existing entry */
-        virPortGroupDefClear(&def->portGroups[ii]);
-        def->portGroups[ii] = portgroup;
+        virPortGroupDefClear(&def->portGroups[foundName]);
+        def->portGroups[foundName] = portgroup;
         memset(&portgroup, 0, sizeof(portgroup));
 
     } else if ((command == VIR_NETWORK_UPDATE_COMMAND_ADD_FIRST) ||
@@ -2816,9 +2833,9 @@ virNetworkDefUpdatePortGroup(virNetworkDefPtr def,
     } else if (command == VIR_NETWORK_UPDATE_COMMAND_DELETE) {
 
         /* remove it */
-        virPortGroupDefClear(&def->portGroups[ii]);
-        memmove(def->portGroups + ii, def->portGroups + ii + 1,
-                sizeof(*def->portGroups) * (def->nPortGroups - ii - 1));
+        virPortGroupDefClear(&def->portGroups[foundName]);
+        memmove(def->portGroups + foundName, def->portGroups + foundName + 1,
+                sizeof(*def->portGroups) * (def->nPortGroups - foundName - 1));
         def->nPortGroups--;
         ignore_value(VIR_REALLOC_N(def->portGroups, def->nPortGroups));
     } else {

src/network/bridge_driver.c

@@ -2618,6 +2618,7 @@ networkValidate(virNetworkDefPtr def)
 {
     int ii;
     bool vlanUsed, vlanAllowed;
+    const char *defaultPortGroup = NULL;
 
     /* The only type of networks that currently support transparent
      * vlan configuration are those using hostdev sr-iov devices from
@@ -2638,6 +2639,17 @@ networkValidate(virNetworkDefPtr def)
              == VIR_NETDEV_VPORT_PROFILE_OPENVSWITCH)) {
             vlanAllowed = true;
         }
+        if (def->portGroups[ii].isDefault) {
+            if (defaultPortGroup) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("network '%s' has multiple default "
+                                 "<portgroup> elements (%s and %s), "
+                                 "but only one default is allowed"),
+                               def->name, defaultPortGroup,
+                               def->portGroups[ii].name);
+            }
+            defaultPortGroup = def->portGroups[ii].name;
+        }
     }
     if (vlanUsed && !vlanAllowed) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,