ARP: add feature arc

- arp-input, registered with the ethernet protocol dispatcher, performs
basic checks and starts the arc
- arp-reply; first feature on the arc replies to requests and learns
from responses (no functional change)
- arp-proxy; checks against the proxy DB

arp-reply and arp-proxy are enabled when the interface is appropriately
configured.

Change-Id: I7d1bbabdb8c8b8187cac75e663daa4a5a7ce382a
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/vnet/ip/ip4.h b/src/vnet/ip/ip4.h
index 31ca10feece..5c9add4c796 100644
--- a/src/vnet/ip/ip4.h
+++ b/src/vnet/ip/ip4.h
@@ -74,6 +74,15 @@ typedef struct
   uword function_opaque;
 } ip4_add_del_interface_address_callback_t;
 
+typedef void (ip4_enable_disable_interface_function_t)
+  (struct ip4_main_t * im, uword opaque, u32 sw_if_index, u32 is_enable);
+
+typedef struct
+{
+  ip4_enable_disable_interface_function_t *function;
+  uword function_opaque;
+} ip4_enable_disable_interface_callback_t;
+
 typedef void (ip4_table_bind_function_t)
   (struct ip4_main_t * im,
    uword opaque, u32 sw_if_index, u32 new_fib_index, u32 old_fib_index);
@@ -129,6 +138,10 @@ typedef struct ip4_main_t
     ip4_add_del_interface_address_callback_t
     * add_del_interface_address_callbacks;
 
+  /** Functions to call when interface becomes IPv4 enabled/disable. */
+    ip4_enable_disable_interface_callback_t
+    * enable_disable_interface_callbacks;
+
   /** Functions to call when interface to table biding changes. */
   ip4_table_bind_callback_t *table_bind_callbacks;