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>

3 files changed, 25 insertions, 17 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;
 
diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index d8eed67a381..9c5524f17a0 100644
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -515,6 +515,12 @@ ip4_sw_interface_enable_disable (u32 sw_if_index, u32 is_enable)
 
   vnet_feature_enable_disable ("ip4-multicast", "ip4-not-enabled",
 			       sw_if_index, !is_enable, 0, 0);
+
+  {
+    ip4_enable_disable_interface_callback_t *cb;
+    vec_foreach (cb, im->enable_disable_interface_callbacks)
+      cb->function (im, cb->function_opaque, sw_if_index, is_enable);
+  }
 }
 
 static clib_error_t *
diff --git a/src/vnet/ip/ip_api.c b/src/vnet/ip/ip_api.c
index f4e5d1776bd..06caf111b91 100644
--- a/src/vnet/ip/ip_api.c
+++ b/src/vnet/ip/ip_api.c
@@ -3019,22 +3019,18 @@ vl_api_proxy_arp_dump_t_handler (vl_api_proxy_arp_dump_t * mp)
 }
 
 static walk_rc_t
-send_proxy_arp_intfc_details (vnet_main_t * vnm,
-			      vnet_sw_interface_t * si, void *data)
+send_proxy_arp_intfc_details (u32 sw_if_index, void *data)
 {
   vl_api_proxy_arp_intfc_details_t *mp;
   proxy_arp_walk_ctx_t *ctx;
 
-  if (!(si->flags & VNET_SW_INTERFACE_FLAG_PROXY_ARP))
-    return (WALK_CONTINUE);
-
   ctx = data;
 
   mp = vl_msg_api_alloc (sizeof (*mp));
   clib_memset (mp, 0, sizeof (*mp));
   mp->_vl_msg_id = ntohs (VL_API_PROXY_ARP_INTFC_DETAILS);
   mp->context = ctx->context;
-  mp->sw_if_index = htonl (si->sw_if_index);
+  mp->sw_if_index = htonl (sw_if_index);
 
   vl_api_send_msg (ctx->reg, (u8 *) mp);
 
@@ -3055,8 +3051,7 @@ vl_api_proxy_arp_intfc_dump_t_handler (vl_api_proxy_arp_intfc_dump_t * mp)
     .context = mp->context,
   };
 
-  vnet_sw_interface_walk (vnet_get_main (),
-			  send_proxy_arp_intfc_details, &wctx);
+  proxy_arp_intfc_walk (send_proxy_arp_intfc_details, &wctx);
 }
 
 static void
@@ -3069,15 +3064,9 @@ static void
 
   VALIDATE_SW_IF_INDEX (mp);
 
-  vnet_sw_interface_t *si =
-    vnet_get_sw_interface (vnm, ntohl (mp->sw_if_index));
-
-  ASSERT (si);
-
-  if (mp->enable_disable)
-    si->flags |= VNET_SW_INTERFACE_FLAG_PROXY_ARP;
-  else
-    si->flags &= ~VNET_SW_INTERFACE_FLAG_PROXY_ARP;
+  rv = vnet_proxy_arp_enable_disable (vnm,
+				      ntohl (mp->sw_if_index),
+				      mp->enable_disable);
 
   BAD_SW_IF_INDEX_LABEL;