tsig_key_table
tsig_key_table = rbtree_create(region, &tree_dname_compare);
(void)rbtree_insert(tsig_key_table, &entry->node);
entry = (tsig_key_table_type*)rbtree_delete(tsig_key_table, key->name);
entry = (tsig_key_table_type*)rbtree_search(tsig_key_table, name);
typedef struct tsig_key_table tsig_key_table_type;
static rbtree_type *tsig_key_table;