Add basic 4o4 LISP unit test

Change-Id: I2d812153d7afe7980346382b525af89b3c47e796
Signed-off-by: Filip Tehlar <ftehlar@cisco.com>

test/util.py

@@ -100,3 +100,16 @@ class Host(object):
         self._mac = mac
         self._ip4 = ip4
         self._ip6 = ip6
+
+
+class ForeignAddressFactory(object):
+    count = 0
+    prefix_len = 24
+    net_template = '10.10.10.{}'
+    net = net_template.format(0) + '/' + str(prefix_len)
+
+    def get_ip4(self):
+        if self.count > 255:
+            raise Exception("Network host address exhaustion")
+        self.count += 1
+        return self.net_template.format(self.count)