zebra: add per-nexthop backup index

Use a backup index in a nexthop directly (if it has a backup
nexthop); revise the zebra nhe/nhg code; revise zapi route
decoding to match; revise the dataplane route datastructs.

Refactor some of the rib_add_multipath code to be prepared to
be called with an nhe, carrying nexthop and (possibly) backup
info together.

Signed-off-by: Mark Stapp <mjs@voltanet.io>

1 files changed, 26 insertions, 1 deletions

diff --git a/zebra/zebra_nhg.h b/zebra/zebra_nhg.h
index dc3a47c020..340de952be 100644
--- a/zebra/zebra_nhg.h
+++ b/zebra/zebra_nhg.h
@@ -50,6 +50,9 @@ struct nhg_hash_entry {
 
 	struct nexthop_group nhg;
 
+	/* If supported, a mapping of backup nexthops. */
+	struct nhg_backup_info *backup_info;
+
 	/* If this is not a group, it
 	 * will be a single nexthop
 	 * and must have an interface
@@ -72,6 +75,7 @@ struct nhg_hash_entry {
 	 * faster with ID's.
 	 */
 	struct nhg_connected_tree_head nhg_depends, nhg_dependents;
+
 /*
  * Is this nexthop group valid, ie all nexthops are fully resolved.
  * What is fully resolved?  It's a nexthop that is either self contained
@@ -102,11 +106,25 @@ struct nhg_hash_entry {
  * from the kernel. Therefore, it is unhashable.
  */
 #define NEXTHOP_GROUP_UNHASHABLE (1 << 4)
+
+/*
+ * Backup nexthop support - identify groups that are backups for
+ * another group.
+ */
+#define NEXTHOP_GROUP_BACKUP (1 << 5)
+
 };
 
 /* Was this one we created, either this session or previously? */
 #define ZEBRA_NHG_CREATED(NHE) ((NHE->type) == ZEBRA_ROUTE_NHG)
 
+/*
+ * Backup nexthops: this is a group object itself, so
+ * that the backup nexthops can use the same code as a normal object.
+ */
+struct nhg_backup_info {
+	struct nhg_hash_entry *nhe;
+};
 
 enum nhg_ctx_op_e {
 	NHG_CTX_OP_NONE = 0,
@@ -162,13 +180,20 @@ bool zebra_nhg_kernel_nexthops_enabled(void);
 
 /**
  * NHE abstracted tree functions.
- * Use these where possible instead of the direct ones access ones.
+ * Use these where possible instead of direct access.
  */
 struct nhg_hash_entry *zebra_nhg_alloc(void);
 void zebra_nhg_free(struct nhg_hash_entry *nhe);
 /* In order to clear a generic hash, we need a generic api, sigh. */
 void zebra_nhg_hash_free(void *p);
 
+/* Allocate, free backup nexthop info objects */
+struct nhg_backup_info *zebra_nhg_backup_alloc(void);
+void zebra_nhg_backup_free(struct nhg_backup_info **p);
+
+struct nhg_hash_entry *zebra_nhg_get_backup_nhe(struct nhg_hash_entry *nhe);
+struct nexthop_group *zebra_nhg_get_backup_nhg(struct nhg_hash_entry *nhe);
+
 extern struct nhg_hash_entry *zebra_nhg_resolve(struct nhg_hash_entry *nhe);
 
 extern unsigned int zebra_nhg_depends_count(const struct nhg_hash_entry *nhe);