ospfd: fix NSSA translate-always

When an ABR NSSA router is configured to be ALWAYS the translator:
  r22(config-router)# area 1 nssa translate-always

It will advertise this condition in the type-1 LSA setting the Nt
bit, taking over the translator role from r33

  r22# show ip ospf
     We are an ABR and always an NSSA Translator.
  r33# show ip ospf
     We are an ABR, but not the NSSA Elected Translator.

However when the command above is removed:
  r22(config-router)# no area 1 nssa translate-always

the bit Nt needs to be cleared otherwise we end up with no translator
in the area
  r22# show ip ospf
     We are an ABR, but not the NSSA Elected Translator.
  r33# show ip ospf
     We are an ABR, but not the NSSA Elected Translator.

This PR forces the ABR to send a type-1 LSA with the Nt bit updated
according to the translator role

Signed-off-by: ckishimo <carles.kishimoto@gmail.com>

diff --git a/ospfd/ospfd.c b/ospfd/ospfd.c
index b375c991192f56c3d8e05aa27d3ba23e2b2ef841..d7c4e108c53f79964beb970a708d5ad87c28b7e6 100644 (file)
--- a/ospfd/ospfd.c
+++ b/ospfd/ospfd.c
@@ -1572,7 +1572,8 @@ int ospf_area_nssa_unset(struct ospf *ospf, struct in_addr area_id, int argc)
                        OSPF_NSSA_TRANS_STABLE_DEFAULT;
                ospf_area_type_set(area, OSPF_AREA_DEFAULT);
        } else {
-               area->NSSATranslatorRole = OSPF_NSSA_ROLE_CANDIDATE;
+               ospf_area_nssa_translator_role_set(ospf, area_id,
+                                                  OSPF_NSSA_ROLE_CANDIDATE);
        }
 
        ospf_area_check_free(ospf, area_id);
@@ -1589,7 +1590,19 @@ int ospf_area_nssa_translator_role_set(struct ospf *ospf,
        if (area == NULL)
                return 0;
 
-       area->NSSATranslatorRole = role;
+       if (role != area->NSSATranslatorRole) {
+               if ((area->NSSATranslatorRole == OSPF_NSSA_ROLE_ALWAYS)
+                   || (role == OSPF_NSSA_ROLE_ALWAYS)) {
+                       /* RFC 3101 3.1
+                        * if new role is OSPF_NSSA_ROLE_ALWAYS we need to set
+                        * Nt bit, if the role was OSPF_NSSA_ROLE_ALWAYS we need
+                        * to clear Nt bit
+                        */
+                       area->NSSATranslatorRole = role;
+                       ospf_router_lsa_update_area(area);
+               } else
+                       area->NSSATranslatorRole = role;
+       }
 
        return 1;
 }