Prevent Bridge Domain operations on BD 0.

The default bridge domain, 0, is created automatically
with static features.  It should be modified by neither
the CLI nor the API.  So add tests for, and reject any
operation on BD 0.  The new API error message BD_NOT_MODIFIABLE
is returned in such cases.

Change-Id: Iaf3dd80c4f43cf41689ca55756a0a3525420cd12
Signed-off-by: Jon Loeliger <jdl@netgate.com>
diff --git a/src/vnet/api_errno.h b/src/vnet/api_errno.h
index b87c197..e694fbf 100644
--- a/src/vnet/api_errno.h
+++ b/src/vnet/api_errno.h
@@ -110,7 +110,8 @@
 _(APPLICATION_NOT_ATTACHED, -118, "application not attached")           \
 _(BD_ALREADY_EXISTS, -119, "Bridge domain already exists")              \
 _(BD_IN_USE, -120, "Bridge domain has member interfaces")		\
-_(UNSUPPORTED, -121, "Unsupported")
+_(BD_NOT_MODIFIABLE, -121, "Default bridge domain 0 can be neither deleted nor modified") \
+_(UNSUPPORTED, -122, "Unsupported")
 
 typedef enum
 {
diff --git a/src/vnet/l2/l2_api.c b/src/vnet/l2/l2_api.c
index 5a3c8dc..8cc7c79 100644
--- a/src/vnet/l2/l2_api.c
+++ b/src/vnet/l2/l2_api.c
@@ -310,7 +310,15 @@
   vl_api_bridge_domain_set_mac_age_reply_t *rmp;
   int rv = 0;
   u32 bd_id = ntohl (mp->bd_id);
-  uword *p = hash_get (bdm->bd_index_by_bd_id, bd_id);
+  uword *p;
+
+  if (bd_id == 0)
+    {
+      rv = VNET_API_ERROR_BD_NOT_MODIFIABLE;
+      goto out;
+    }
+
+  p = hash_get (bdm->bd_index_by_bd_id, bd_id);
   if (p == 0)
     {
       rv = VNET_API_ERROR_NO_SUCH_ENTRY;
@@ -401,10 +409,13 @@
     return;
 
   bd_id = ntohl (mp->bd_id);
+  if (bd_id == 0)
+    return;
 
   bd_index = (bd_id == ~0) ? 0 : bd_find_index (bdm, bd_id);
   ASSERT (bd_index != ~0);
   end = (bd_id == ~0) ? vec_len (l2im->bd_configs) : bd_index + 1;
+
   for (; bd_index < end; bd_index++)
     {
       bd_config = l2input_bd_config_from_index (l2im, bd_index);
@@ -437,6 +448,12 @@
   u32 flags = ntohl (mp->feature_bitmap);
   uword *p;
 
+  if (bd_id == 0)
+    {
+      rv = VNET_API_ERROR_BD_NOT_MODIFIABLE;
+      goto out;
+    }
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
   if (p == 0)
     {
diff --git a/src/vnet/l2/l2_bd.c b/src/vnet/l2/l2_bd.c
index 7c55789..4ebbb54 100644
--- a/src/vnet/l2/l2_bd.c
+++ b/src/vnet/l2/l2_bd.c
@@ -304,6 +304,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
   if (p == 0)
@@ -369,6 +373,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
   if (p == 0)
@@ -436,6 +444,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
   if (p == 0)
@@ -502,6 +514,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
   if (p == 0)
@@ -568,6 +584,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
   if (p)
     bd_index = *p;
@@ -607,6 +627,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
   if (p == 0)
@@ -780,6 +804,10 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    return clib_error_return (0,
+			      "No operations on the default bridge domain are supported");
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
   if (p)
@@ -900,7 +928,7 @@
   u32 bd_id = ~0;
   uword *p;
 
-  start = 0;
+  start = 1;
   end = vec_len (l2input_main.bd_configs);
 
   if (unformat (input, "%d", &bd_id))
@@ -914,6 +942,10 @@
       if (unformat (input, "arp"))
 	arp = 1;
 
+      if (bd_id == 0)
+	return clib_error_return (0,
+				  "No operations on the default bridge domain are supported");
+
       p = hash_get (bdm->bd_index_by_bd_id, bd_id);
       if (p)
 	bd_index = *p;
@@ -1125,6 +1157,8 @@
     {
       if (bd_index == ~0)
 	return VNET_API_ERROR_NO_SUCH_ENTRY;
+      if (bd_index == 0)
+	return VNET_API_ERROR_BD_NOT_MODIFIABLE;
       if (vec_len (l2input_main.bd_configs[bd_index].members))
 	return VNET_API_ERROR_BD_IN_USE;
       rv = bd_delete (bdm, bd_index);
@@ -1188,6 +1222,12 @@
       goto done;
     }
 
+  if (bd_id == 0)
+    {
+      error = clib_error_return (0, "bridge domain 0 can not be modified");
+      goto done;
+    }
+
   if (mac_age > 255)
     {
       error = clib_error_return (0, "mac age must be less than 256");
@@ -1218,6 +1258,9 @@
     case VNET_API_ERROR_NO_SUCH_ENTRY:
       error = clib_error_return (0, "bridge domain id does not exist");
       goto done;
+    case VNET_API_ERROR_BD_NOT_MODIFIABLE:
+      error = clib_error_return (0, "bridge domain 0 can not be modified");
+      goto done;
     default:
       error = clib_error_return (0, "bd_add_del returned %d", rv);
       goto done;
diff --git a/src/vpp/api/api.c b/src/vpp/api/api.c
index 9c23057..baf45d5 100644
--- a/src/vpp/api/api.c
+++ b/src/vpp/api/api.c
@@ -446,6 +446,12 @@
   u32 bd_index;
   uword *p;
 
+  if (bd_id == 0)
+    {
+      rv = VNET_API_ERROR_BD_NOT_MODIFIABLE;
+      goto out;
+    }
+
   p = hash_get (bdm->bd_index_by_bd_id, bd_id);
   if (p == 0)
     {