zebra: lingering IP address after deletion (BZ#486)

zebra address bookkeeping is a mess. this is just a workaround to have
IPv4 address deletion somewhat working on Linux.

the if_unset_prefix call is synchronous, when it returns success the
address deletion completed successfully. this is either signaled by a
netlink ACK or by an OK return value from ioctl().

This version is wrapped by #ifdef HAVE_NETLINK so we don't touch the
BSDs for now.

* zebra/interface.c: On Linux, update zebra internal state after
  deleting an address.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/zebra/interface.c b/zebra/interface.c
index 2242259..3578b79 100644
--- a/zebra/interface.c
+++ b/zebra/interface.c
@@ -1297,14 +1297,29 @@
 	       safe_strerror(errno), VTY_NEWLINE);
       return CMD_WARNING;
     }
+  /* success! call returned that the address deletion went through.
+   * this is a synchronous operation, so we know it succeeded and can
+   * now update all internal state. */
 
-#if 0
-  /* Redistribute this information. */
-  zebra_interface_address_delete_update (ifp, ifc);
+  /* the HAVE_NETLINK check is only here because, on BSD, although the
+   * call above is still synchronous, we get a second confirmation later
+   * through the route socket, and we don't want to touch that behaviour
+   * for now.  It should work without the #ifdef, but why take the risk...
+   * -- equinox 2012-07-13 */
+#ifdef HAVE_NETLINK
 
   /* Remove connected route. */
   connected_down_ipv4 (ifp, ifc);
 
+  /* Redistribute this information. */
+  zebra_interface_address_delete_update (ifp, ifc);
+
+  /* IP address propery set. */
+  UNSET_FLAG (ifc->conf, ZEBRA_IFC_REAL);
+
+  /* remove from interface, remark secondaries */
+  if_subnet_delete (ifp, ifc);
+
   /* Free address information. */
   listnode_delete (ifp->connected, ifc);
   connected_free (ifc);