ospfd: Optimize and improve SPF nexthop calculation

Maintain router LSA positions in OSPF interface.
    Find the OSPF interface in nexthop_calculation using
    the position in the router LSA.

    This has the following advantages:
    - Multiple numbered PtP interfaces with the same IP address
      between the same two routers.
    - Use Unnumbered PtP on just one end of the link.
    - Faster OI lookup for the OSPF interface and only
      done once for PtoP links.

*ospf_interface.h: (struct ospf_interface) Add storage for
		   storing router LSA position.

*ospf_interface.c: (ospf_if_lookup_by_lsa_pos)
		   lookup OSPF I/F in an area using LSA position.
		   (ospf_lsa_pos_set) assign LSA position to OSPF
		   interface.

*ospf_lsa.c: (router_lsa_link_set) Call ospf_lsa_pos_set() to record
             LSA position.

*ospf_spf.c: (ospf_spf_next) Count and pass along lsa position.
	     (ospf_nexthop_calculation) Add lsa position argument.
	     call ospf_if_lookup_by_lsa_pos() for OSFP interface handle.
	     Clean up and remove all calls ospf_if_is_configured() the
	     rest. Adjust a few debug logs.

1 files changed, 27 insertions, 1 deletions

diff --git a/ospfd/ospf_interface.c b/ospfd/ospf_interface.c
index 775b121f..67e34f21 100644
--- a/ospfd/ospf_interface.c
+++ b/ospfd/ospf_interface.c
@@ -211,7 +211,9 @@ ospf_if_new (struct ospf *ospf, struct interface *ifp, struct prefix *p)
     }
   else
     return oi;
-    
+
+  ospf_lsa_pos_set(-1,-1, oi); /* delete position in router LSA */
+
   /* Set zebra interface pointer. */
   oi->ifp = ifp;
   oi->address = p;
@@ -397,6 +399,29 @@ ospf_if_exists (struct ospf_interface *oic)
   return NULL;
 }
 
+/* Lookup OSPF interface by router LSA posistion */
+struct ospf_interface *
+ospf_if_lookup_by_lsa_pos (struct ospf_area *area, int lsa_pos)
+{
+  struct listnode *node;
+  struct ospf_interface *oi;
+
+  for (ALL_LIST_ELEMENTS_RO (area->oiflist, node, oi))
+    {
+      if (lsa_pos >= oi->lsa_pos_beg && lsa_pos < oi->lsa_pos_end)
+	return oi;
+    }
+  return NULL;
+}
+
+/* Set OSPF interface position in router LSA */
+void
+ospf_lsa_pos_set(int pos_beg, int pos_end, struct ospf_interface *oi)
+{
+  oi->lsa_pos_beg = pos_beg;
+  oi->lsa_pos_end = pos_end;
+}
+
 struct ospf_interface *
 ospf_if_lookup_by_local_addr (struct ospf *ospf,
 			      struct interface *ifp, struct in_addr address)
@@ -817,6 +842,7 @@ ospf_if_down (struct ospf_interface *oi)
     return 0;
 
   OSPF_ISM_EVENT_EXECUTE (oi, ISM_InterfaceDown);
+  ospf_lsa_pos_set(-1, -1, oi); /* delete position in router LSA */
   /* Shutdown packet reception and sending */
   ospf_if_stream_unset (oi);