Destroying unused network interfaces via VBoxManage

lib/vagrant/action/vm/destroy_unused_network_interfaces.rb

@@ -9,17 +9,7 @@ module Vagrant
         end
 
         def call(env)
-          # Destroy all the host only network adapters which are empty.
+          env[:vm].driver.delete_unused_host_only_networks
-          VirtualBox::Global.global(true).host.network_interfaces.each do |iface|
-            # We only care about host only interfaces
-            next if iface.interface_type != :host_only
-
-            # Destroy it if there is nothing attached
-            if iface.attached_vms.empty?
-              env[:ui].info I18n.t("vagrant.actions.vm.destroy_network.destroying")
-              iface.destroy
-            end
-          end
 
           # Continue along
           @app.call(env)

lib/vagrant/driver/virtualbox.rb

@@ -52,6 +52,28 @@ module Vagrant
         execute("unregistervm", @uuid, "--delete")
       end
 
+      # Deletes any host only networks that aren't being used for anything.
+      def delete_unused_host_only_networks
+        networks = []
+        execute("list", "hostonlyifs").split("\n").each do |line|
+          networks << $1.to_s if line =~ /^Name:\s+(.+?)$/
+        end
+
+        execute("list", "vms").split("\n").each do |line|
+          if line =~ /^".+?"\s+{(.+?)}$/
+            execute("showvminfo", $1.to_s, "--machinereadable").split("\n").each do |info|
+              if info =~ /^hostonlyadapter\d+="(.+?)"$/
+                networks.delete($1.to_s)
+              end
+            end
+          end
+        end
+
+        networks.each do |name|
+          execute("hostonlyif", "remove", name)
+        end
+      end
+
       # Forwards a set of ports for a VM.
       #
       # This will not affect any previously set forwarded ports,