Better handling of global addresses as configured NBMA neighbors in OSPFv3.

Configured NBMA neighbors in OSPFv3 should be link-local addresses, old
behavior was to silently ignore global ones. The patch allows BIRD to
accept global ones, but adds a warning and a documentation notice.

Thanks to Wilco Baan Hofman for the bugreport.

doc/bird.sgml

@@ -2212,7 +2212,10 @@ protocol ospf <name> {
 	<tag>neighbors { <m/set/ } </tag>
 	 A set of neighbors to which Hello messages on NBMA or PtMP
 	 networks are to be sent. For NBMA networks, some of them
-	 could be marked as eligible.
+	 could be marked as eligible. In OSPFv3, link-local addresses
+	 should be used, using global ones is possible, but it is
+	 nonstandard and might be problematic. And definitely,
+	 link-local and global addresses should not be mixed.
 
 </descrip>
 

proto/ospf/config.Y

@@ -135,6 +135,7 @@ CF_KEYWORDS(GLOBAL, LSID, ROUTER, SELF, INSTANCE, REAL)
 
 %type <t> opttext
 %type <ld> lsadb_args
+%type <i> nbma_eligible
 
 CF_GRAMMAR
 
@@ -295,7 +296,7 @@ ospf_iface_item:
  | STUB bool { OSPF_PATT->stub = $2 ; }
  | CHECK LINK bool { OSPF_PATT->check_link = $3; }
  | ECMP WEIGHT expr { OSPF_PATT->ecmp_weight = $3 - 1; if (($3<1) || ($3>256)) cf_error("ECMP weight must be in range 1-256"); }
- | NEIGHBORS '{' ipa_list '}'
+ | NEIGHBORS '{' nbma_list '}'
  | AUTHENTICATION NONE { OSPF_PATT->autype = OSPF_AUTH_NONE ; }
  | AUTHENTICATION SIMPLE { OSPF_PATT->autype = OSPF_AUTH_SIMPLE ; }
  | AUTHENTICATION CRYPTOGRAPHIC { OSPF_PATT->autype = OSPF_AUTH_CRYPT ; }
@@ -327,34 +328,25 @@ pref_opt:
  | TAG expr { this_pref->tag = $2; }
  ;
 
-ipa_list:
+nbma_list:
  /* empty */
- | ipa_list ipa_item
+ | nbma_list nbma_item
  ;
 
-ipa_item:
+nbma_eligible:
-    ipa_el
+ /* empty */ { $$ = 0; }
-  | ipa_ne;
+ | ELIGIBLE { $$ = 1; }
+ ;
  
-ipa_el: IPA ';'
+nbma_item: IPA nbma_eligible ';'
  {
    this_nbma = cfg_allocz(sizeof(struct nbma_node));
    add_tail(&OSPF_PATT->nbma_list, NODE this_nbma);
    this_nbma->ip=$1;
-   this_nbma->eligible=0;
+   this_nbma->eligible=$2;
  }
 ;
  
-ipa_ne: IPA ELIGIBLE ';'
- {
-   this_nbma = cfg_allocz(sizeof(struct nbma_node));
-   add_tail(&OSPF_PATT->nbma_list, NODE this_nbma);
-   this_nbma->ip=$1;
-   this_nbma->eligible=1;
- }
-;
-
- 
 ospf_iface_start:
  {
   this_ipatt = cfg_allocz(sizeof(struct ospf_iface_patt));

proto/ospf/iface.c

@@ -574,8 +574,22 @@ ospf_iface_new(struct ospf_area *oa, struct ifa *addr, struct ospf_iface_patt *i
   init_list(&ifa->nbma_list);
 
   WALK_LIST(nb, ip->nbma_list)
-    if (ipa_in_net(nb->ip, addr->prefix, addr->pxlen))
+  {
-      add_nbma_node(ifa, nb, 0);
+    /* In OSPFv3, addr is link-local while configured neighbors could
+       have global IP (although RFC 5340 C.5 says link-local addresses
+       should be used). Because OSPFv3 iface is not subnet-specific,
+       there is no need for ipa_in_net() check */
+
+#ifdef OSPFv2
+    if (!ipa_in_net(nb->ip, addr->prefix, addr->pxlen))
+      continue;
+#else
+    if (!ipa_has_link_scope(nb->ip))
+      log(L_WARN "In OSPFv3, configured neighbor address (%I) should be link-local", nb->ip);
+#endif
+
+    add_nbma_node(ifa, nb, 0);
+  }
 
   ifa->state = OSPF_IS_DOWN;
   add_tail(&oa->po->iface_list, NODE ifa);
@@ -771,8 +785,14 @@ ospf_iface_reconfigure(struct ospf_iface *ifa, struct ospf_iface_patt *new)
   /* NBMA LIST - add new */
   WALK_LIST(nb, new->nbma_list)
   {
+    /* See related note in ospf_iface_new() */
+#ifdef OSPFv2
     if (!ipa_in_net(nb->ip, ifa->addr->prefix, ifa->addr->pxlen))
       continue;
+#else
+    if (!ipa_has_link_scope(nb->ip))
+      log(L_WARN "In OSPFv3, configured neighbor address (%I) should be link-local", nb->ip);
+#endif
 
     if (! find_nbma_node(ifa, nb->ip))
     {