add consistency in_network for IPOption

This new consistency can validate that an IPv4 is a specified (network/netmask) network

tiramisu/option.py

@@ -784,6 +784,18 @@ class IPOption(Option):
         if self._private_only and not ip.iptype() == 'PRIVATE':
             raise ValueError(_("invalid IP, must be in private class"))
 
+    def _cons_in_network(self, opts, vals):
+        if len(vals) != 3:
+            raise ConfigError(_('invalid len for vals'))
+        if None in vals:
+            return
+        ip, network, netmask = vals
+        if IP(ip) not in IP('{0}/{1}'.format(network, netmask)):
+            raise ValueError(_('invalid IP {0} ({1}) with network {2} '
+                               '({3}) and netmask {4} ({5})').format(
+                                   ip, opts[0]._name, network,
+                                   opts[1]._name, netmask, opts[2]._name))
+
 
 class PortOption(Option):
     """represents the choice of a port