added class to wait until routable

I haven't tested this properly yet

naxalnet/network.py

@@ -30,6 +30,7 @@ examples.
 import subprocess
 from pathlib import Path
 from dasbus.connection import SystemMessageBus
+from dasbus.loop import EventLoop
 
 
 NETWORKD_BUS = "org.freedesktop.network1"
@@ -118,3 +119,54 @@ class NetworkD:
         """
         for i in self.runtime_path.iterdir():
             self.remove_config(i.name)
+
+
+class NetworkLoop(NetworkD):
+    """Used to wait until a condition is met
+
+    Available methods:
+
+    NetworkLoop.wait_until_routable(timeout=0):
+        return true when the network is routable, or false when timed out
+
+    """
+
+    def __init__(self, *args, **kwargs):
+        # first, initialise the parent object
+        super().__init__(*args, **kwargs)
+        self.waitfor = None
+        self.wait_function = None
+        self.loop = EventLoop()
+
+    def start_loop(self):
+        """start the dasbus loop"""
+        self.proxy.PropertiesChanged.connect(self.on_properties_changed)
+        self.loop.run()
+
+    def wait_until_routable(self, timeout=0):
+        """
+        wait until timeout in milliseconds and returns True when any
+        network interface is shown routable by networkd
+        """
+        self.wait_for_change("AddressState", self.on_addressstate_change)
+        return self.is_routable()
+
+    def wait_for_change(self, name, function):
+        """used by the public functions"""
+        self.waitfor = name
+        self.wait_function = function
+        self.start_loop()
+
+    def on_addressstate_change(self):
+        """quit the loop if the network is routable"""
+        if self.is_routable():
+            self.loop.quit()
+
+    def on_properties_changed(self, bus_interface, data, blah):
+        """give this function some documentation"""
+        if self.waitfor in data:
+            return self.wait_function()
+
+    def on_timeout(self):
+        """called by dasbus when a timeout occurs"""
+        self.loop.quit()