Set prefix on floating_ip_mangle rules

Set the /32 prefix that iptables will automatically do internally
so our format matches the iptables-save format and we don't
unnecessarily re-apply rules.

Testing for this is provided by enabling the IPTables convergence
check in I6bee1d51155488e91857ee8bc45470d6a224fa37

Closes-Bug: #1607699
Change-Id: I0088636d2f8409f0f6f17b3ed2288f6edfac1e68

neutron/agent/l3/dvr_local_router.py

@@ -77,10 +77,10 @@ class DvrLocalRouter(dvr_router_base.DvrRouterBase):
 
         rtr_2_fip_name = self.fip_ns.get_rtr_ext_device_name(self.router_id)
         mark_traffic_to_floating_ip = (
-            'floatingip', '-d %s -i %s -j MARK --set-xmark %s' % (
+            'floatingip', '-d %s/32 -i %s -j MARK --set-xmark %s' % (
                 floating_ip, rtr_2_fip_name, internal_mark))
         mark_traffic_from_fixed_ip = (
-            'FORWARD', '-s %s -j $float-snat' % fixed_ip)
+            'FORWARD', '-s %s/32 -j $float-snat' % fixed_ip)
         return [mark_traffic_to_floating_ip, mark_traffic_from_fixed_ip]
 
     def floating_ip_added_dist(self, fip, fip_cidr):

neutron/agent/l3/router_info.py

@@ -155,10 +155,10 @@ class RouterInfo(object):
 
     def floating_mangle_rules(self, floating_ip, fixed_ip, internal_mark):
         mark_traffic_to_floating_ip = (
-            'floatingip', '-d %s -j MARK --set-xmark %s' % (
+            'floatingip', '-d %s/32 -j MARK --set-xmark %s' % (
                 floating_ip, internal_mark))
         mark_traffic_from_fixed_ip = (
-            'FORWARD', '-s %s -j $float-snat' % fixed_ip)
+            'FORWARD', '-s %s/32 -j $float-snat' % fixed_ip)
         return [mark_traffic_to_floating_ip, mark_traffic_from_fixed_ip]
 
     def get_address_scope_mark_mask(self, address_scope=None):