lib: Add vrf_lookup_by_table with hashmap to vrf.c[h]

Lookup uses hashmap with table_id key and vrf_id values.
Only for vrf backended by vrf lite. Could do similar
implementation with ns_id in future.

Hashmap local to vrf.c but must be updated when
vrf is added or modified. For updates to vrf_id,
call to helper function vrf_ids_by_table_update()
is added in the publicly used vrf_update() function.

Previously, the table_id was set by directly modifying
vrf->data.l.table_id in zclient.c. However, as no functions
in vrf.c are notified when change occurs, a helper function,
vrf_update_table_id(), is added. This both updates
vrf_data.l.table_id, and updates the local hashmap.

vrf_delete() function used for removing vrfs. Add call to
here to vrf_ids_by_table_delete() helper function
to remove entries from hashmap.

Signed-off-by: Nathan Duddles <duddles.nathan@gmail.com>

lib/vrf.c

@@ -20,6 +20,7 @@
  */
 
 #include <zebra.h>
+#include "zebra/zebra_vrf.h"
 
 #include "if.h"
 #include "vrf.h"
@@ -57,6 +58,62 @@ static int vrf_backend;
 static int vrf_backend_configured;
 static char vrf_default_name[VRF_NAMSIZ] = VRF_DEFAULT_NAME_INTERNAL;
 
+/*Hash Table for table_id based lookup of vrf_id*/
+PREDECL_HASH(vrf_ids_by_table);
+
+struct vrf_ids_by_table_proxy {
+	struct vrf_ids_by_table_item vrf_ids_by_table_hash_item;
+	uint32_t table_id;
+	vrf_id_t vrf_id;
+};
+
+static struct vrf_ids_by_table_head vrf_ids_by_table_head;
+
+static int vrf_ids_by_table_cmp(const struct vrf_ids_by_table_proxy *item_a,
+				const struct vrf_ids_by_table_proxy *item_b)
+{
+	return (item_a->table_id == item_b->table_id);
+}
+
+static uint32_t vrf_ids_by_table_hash(const struct vrf_ids_by_table_proxy *item)
+{
+	return item->table_id;
+}
+
+DECLARE_HASH(vrf_ids_by_table, struct vrf_ids_by_table_proxy,
+	     vrf_ids_by_table_hash_item, vrf_ids_by_table_cmp,
+	     vrf_ids_by_table_hash);
+
+/* Helper functions for vrf_ids_by_table hashmap */
+static void vrf_ids_by_table_delete(uint32_t table_id, vrf_id_t vrf_id)
+{
+	struct vrf_ids_by_table_proxy ref = {.table_id = table_id};
+	struct vrf_ids_by_table_proxy *item =
+		vrf_ids_by_table_find(&vrf_ids_by_table_head, &ref);
+
+	/* If entry contains both table_id and vrf_id, remove from hashmap */
+	if (item != NULL && item->vrf_id == vrf_id) {
+		vrf_ids_by_table_del(&vrf_ids_by_table_head, &ref);
+	}
+}
+
+static void vrf_ids_by_table_update(uint32_t table_id, vrf_id_t new_vrf_id)
+{
+	struct vrf_ids_by_table_proxy ref = {.table_id = table_id,
+					     .vrf_id = new_vrf_id};
+
+	/* If not already in hashmap, adds and returns null;
+	 * otherwise returns current entry
+	 */
+	struct vrf_ids_by_table_proxy *item =
+		vrf_ids_by_table_add(&vrf_ids_by_table_head, &ref);
+
+	/* If current entry with table_id, then update */
+	if (item != NULL) {
+		item->vrf_id = new_vrf_id;
+	}
+}
+
 /*
  * Turn on/off debug code
  * for vrf.
@@ -150,6 +207,7 @@ struct vrf *vrf_get(vrf_id_t vrf_id, const char *name)
 	if (!vrf && vrf_id != VRF_UNKNOWN)
 		vrf = vrf_lookup_by_id(vrf_id);
 
+	/* Unable to find VRF by either ID or name, so create */
 	if (vrf == NULL) {
 		vrf = XCALLOC(MTYPE_VRF, sizeof(struct vrf));
 		vrf->vrf_id = VRF_UNKNOWN;
@@ -200,6 +258,7 @@ struct vrf *vrf_update(vrf_id_t new_vrf_id, const char *name)
 
 	/*Treat VRF add for existing vrf as update
 	 * Update VRF ID and also update in VRF ID table
+	 * and also update in vrf_ids_by_table hashmap
 	 */
 	if (name)
 		vrf = vrf_lookup_by_name(name);
@@ -222,6 +281,9 @@ struct vrf *vrf_update(vrf_id_t new_vrf_id, const char *name)
 		vrf->vrf_id = new_vrf_id;
 		RB_INSERT(vrf_id_head, &vrfs_by_id, vrf);
 
+		/* Update hash map */
+		vrf_ids_by_table_update(vrf->data.l.table_id, new_vrf_id);
+
 	} else {
 
 		/*
@@ -232,6 +294,38 @@ struct vrf *vrf_update(vrf_id_t new_vrf_id, const char *name)
 	return vrf;
 }
 
+/* Update table_id in existing VRF.
+ * Arg:
+ *   vrf          - pointer to vrf struct.
+ *   new_table_id - The table_id to be saved to vrf struct.
+ * Description: This function first checks if vrf struct has matching table_id
+ * matching new_table_id arg. If so, it ensures entry is created in
+ * vrf_ids_by_table hashmap and returns. If not matching, then it removes
+ * previous entry and adds new entry with new_table_id.
+ * Finally, it updates the table_id in the vrf struct.
+ */
+void vrf_update_table_id(struct vrf *vrf, uint32_t new_table_id)
+{
+
+	/* If new and old table ids are same */
+	if (new_table_id == vrf->data.l.table_id) {
+
+		/* Ensure that entry is added to hash map */
+		vrf_ids_by_table_update(new_table_id, vrf->vrf_id);
+
+		return;
+	}
+
+	/* New and old table ids are different
+	 * so remove any entry with old table_id and vrf_id, and add new entry
+	 */
+	vrf_ids_by_table_delete(vrf->data.l.table_id, vrf->vrf_id);
+	vrf_ids_by_table_update(new_table_id, vrf->vrf_id);
+
+	/*Update table_id in vrf struct */
+	vrf->data.l.table_id = new_table_id;
+}
+
 /* Delete a VRF. This is called when the underlying VRF goes away, a
  * pre-configured VRF is deleted or when shutting down (vrf_terminate()).
  */
@@ -263,6 +357,9 @@ void vrf_delete(struct vrf *vrf)
 	if (vrf_master.vrf_delete_hook)
 		(*vrf_master.vrf_delete_hook)(vrf);
 
+	/* remove from vrf_ids_by_table hash map*/
+	vrf_ids_by_table_delete(vrf->data.l.table_id, vrf->vrf_id);
+
 	QOBJ_UNREG(vrf);
 
 	if (vrf->name[0] != '\0')
@@ -279,6 +376,51 @@ struct vrf *vrf_lookup_by_id(vrf_id_t vrf_id)
 	return (RB_FIND(vrf_id_head, &vrfs_by_id, &vrf));
 }
 
+/* Finds vrf_id of vrf with table_id or ns_id.
+ *
+ * table_id
+ *    The table_id associated with vrf of interest
+ *
+ * ns_id
+ *    The ns_id associated with vrf of interest
+ *
+ * Description:
+ *    This function checks if vrf is backened by netns
+ *    or vrf lite, and looks them up appropriately.
+ *    Hashmap look up implemented for vrf lite, but not netns.
+ *
+ * Returns:
+ *    vrf_id if found table by table_id, or VRF_DEFAULT if not found
+ */
+vrf_id_t vrf_lookup_by_table(uint32_t table_id, ns_id_t ns_id)
+{
+	struct vrf *vrf;
+	struct zebra_vrf *zvrf;
+
+	/* case vrf with netns : match the netnsid */
+	if (vrf_is_backend_netns()) {
+		RB_FOREACH (vrf, vrf_id_head, &vrfs_by_id) {
+			zvrf = vrf->info;
+			if (zvrf == NULL)
+				continue;
+			if (ns_id == zvrf_id(zvrf))
+				return zvrf_id(zvrf);
+		}
+		/* case vrf with VRF_BACKEND_VRF_LITE : match the table_id */
+	} else if (vrf_get_backend() == VRF_BACKEND_VRF_LITE) {
+
+		struct vrf_ids_by_table_proxy ref = {.table_id = table_id};
+
+		struct vrf_ids_by_table_proxy *found_entry =
+			vrf_ids_by_table_find(&vrf_ids_by_table_head, &ref);
+		if (found_entry != NULL) {
+			return found_entry->vrf_id;
+		}
+	}
+
+	return VRF_DEFAULT;
+}
+
 /*
  * Enable a VRF - that is, let the VRF be ready to use.
  * The VRF_ENABLE_HOOK callback will be called to inform

lib/vrf.h

@@ -116,8 +116,10 @@ extern struct vrf_name_head vrfs_by_name;
 
 extern struct vrf *vrf_lookup_by_id(vrf_id_t);
 extern struct vrf *vrf_lookup_by_name(const char *);
+extern vrf_id_t vrf_lookup_by_table(uint32_t table_id, ns_id_t ns_id);
 extern struct vrf *vrf_get(vrf_id_t, const char *);
 extern struct vrf *vrf_update(vrf_id_t new_vrf_id, const char *name);
+extern void vrf_update_table_id(struct vrf *vrf, uint32_t new_table_id);
 extern const char *vrf_id_to_name(vrf_id_t vrf_id);
 
 #define VRF_LOGNAME(V) V ? V->name : "Unknown"

lib/zclient.c

@@ -2150,7 +2150,9 @@ static int zclient_vrf_add(ZAPI_CALLBACK_ARGS)
 	if (!vrf)
 		return 0;
 
-	vrf->data.l.table_id = data.l.table_id;
+	/* set the vrf table_id if created*/
+	vrf_update_table_id(vrf, data.l.table_id);
+
 	memcpy(vrf->data.l.netns_name, data.l.netns_name, NS_NAMSIZ);
 	vrf_enable(vrf);