feature: add vnet_feature_is_enabled

A predicate function which says whether a given sw_if_index has a
certain feature enabled.

int vnet_feature_is_enabled (const char *arc_name,
                             const char *feature_node_name,
                             u32 sw_if_index)

returns 1 if the feature is enabled
returns 0 if the feature is not enabled
returns VNET_API_ERROR_INVALID_VALUE if the arc name is not found
returns VNET_API_ERROR_INVALID_VALUE_2 if the feature node name is not found
returns VNET_API_ERROR_INVALID_SW_IF_INDEX if the sw_if_index is not found

Type: improvement
Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: Id9ed53e2ae9252efc750ae80fd610456b95cefa4

2 files changed, 60 insertions, 1 deletions

diff --git a/src/vnet/feature/feature.c b/src/vnet/feature/feature.c
index 09dd9cc965f..1bdd695e1de 100644
--- a/src/vnet/feature/feature.c
+++ b/src/vnet/feature/feature.c
@@ -15,7 +15,6 @@
 
 #include <vnet/feature/feature.h>
 
-
 vnet_feature_main_t feature_main;
 
 typedef struct vnet_feature_upd_registration_t_
@@ -321,6 +320,62 @@ vnet_feature_enable_disable (const char *arc_name, const char *node_name,
 						 n_feature_config_bytes);
 }
 
+int
+vnet_feature_is_enabled (const char *arc_name, const char *feature_node_name,
+			 u32 sw_if_index)
+{
+  vnet_feature_main_t *fm = &feature_main;
+  vnet_feature_config_main_t *cm;
+  vnet_config_main_t *ccm;
+  vnet_config_t *current_config;
+  vnet_config_feature_t *f;
+  u32 feature_index;
+  u32 ci;
+  u8 arc_index;
+  u32 *p;
+
+  arc_index = vnet_get_feature_arc_index (arc_name);
+
+  /* No such arc? */
+  if (arc_index == (u8) ~ 0)
+    return VNET_API_ERROR_INVALID_VALUE;
+
+  feature_index = vnet_get_feature_index (arc_index, feature_node_name);
+
+  /* No such feature? */
+  if (feature_index == (u32) ~ 0)
+    return VNET_API_ERROR_INVALID_VALUE_2;
+
+  cm = &fm->feature_config_mains[arc_index];
+
+  if (sw_if_index < vec_len (cm->config_index_by_sw_if_index))
+    ci = vec_elt (cm->config_index_by_sw_if_index, sw_if_index);
+  else
+    /* sw_if_index out of range, certainly not enabled */
+    return VNET_API_ERROR_INVALID_SW_IF_INDEX;
+
+  /* No features were ever configured? */
+  if (ci == ~0)
+    return 0;
+
+  ccm = &cm->config_main;
+
+  p = heap_elt_at_index (ccm->config_string_heap, ci);
+
+  current_config = pool_elt_at_index (ccm->config_pool, p[-1]);
+
+  /* Find feature with the required index */
+  vec_foreach (f, current_config->features)
+  {
+    if (f->feature_index == feature_index)
+      /* Feature was enabled */
+      return 1;
+  }
+  /* feature wasn't enabled */
+  return 0;
+}
+
+
 u32
 vnet_feature_modify_end_node (u8 arc_index,
 			      u32 sw_if_index, u32 end_node_index)
diff --git a/src/vnet/feature/feature.h b/src/vnet/feature/feature.h
index 6eb6de3fba7..9aa32182ef6 100644
--- a/src/vnet/feature/feature.h
+++ b/src/vnet/feature/feature.h
@@ -488,6 +488,10 @@ typedef void (*vnet_feature_update_cb_t) (u32 sw_if_index,
 
 extern void vnet_feature_register (vnet_feature_update_cb_t cb, void *data);
 
+int
+vnet_feature_is_enabled (const char *arc_name, const char *feature_node_name,
+			 u32 sw_if_index);
+
 #endif /* included_feature_h */
 
 /*