Better selection of link-local NLRI addresses, at least for our own

address. Need to do it better for the other neighbors -- the current
solution works only if they use the standard 64+64 global addresses
and the interface identifier in lower 64 bits is the same as for the
link-scope addresses.

3 files changed, 26 insertions, 5 deletions

diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
index f6cbed4..7069d98 100644
--- a/proto/bgp/bgp.c
+++ b/proto/bgp/bgp.c
@@ -434,6 +434,19 @@ bgp_start_neighbor(struct bgp_proto *p)
 {
   p->local_addr = p->neigh->iface->addr->ip;
   DBG("BGP: local=%I remote=%I\n", p->local_addr, p->next_hop);
+#ifdef IPV6
+  {
+    struct ifa *a;
+    p->local_link = ipa_or(ipa_build(0xfe80,0,0,0), ipa_and(p->local_addr, ipa_build(0,0,~0,~0)));
+    WALK_LIST(a, p->neigh->iface->addrs)
+      if (a->scope == SCOPE_LINK)
+        {
+	  p->local_link = a->ip;
+	  break;
+	}
+    DBG("BGP: Selected link-level address %I\n", p->local_link);
+  }
+#endif
   bgp_initiate(p);
 }
 
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index 03f47f9..6519db8 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -74,6 +74,7 @@ struct bgp_proto {
 #ifdef IPV6
   byte *mp_reach_start, *mp_unreach_start; /* Multiprotocol BGP attribute notes */
   unsigned mp_reach_len, mp_unreach_len;
+  ip_addr local_link;			/* Link-level version of local_addr */
 #endif
 };
 
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index bf89343..03b2211 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -193,20 +193,27 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
 	  nh = ea_find(buck->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
 	  ASSERT(nh);
 	  ip = *(ip_addr *) nh->u.ptr->data;
+	  is_ll = 0;
 	  if (ipa_equal(ip, p->local_addr))
-	    is_ll = 1;
+	    {
+	      is_ll = 1;
+	      ip_ll = p->local_link;
+	    }
 	  else
 	    {
 	      n = neigh_find(&p->p, &ip, 0);
 	      if (n && n->iface == p->neigh->iface)
-		is_ll = 1;
-	      else
-		is_ll = 0;
+		{
+		  /* FIXME: We are assuming the global scope addresses use the lower 64 bits
+		   * as an interface identifier which hasn't necessarily to be true.
+		   */
+		  is_ll = 1;
+	          ip_ll = ipa_or(ipa_build(0xfe800000,0,0,0), ipa_and(ip, ipa_build(0,0,~0,~0)));
+		}
 	    }
 	  if (is_ll)
 	    {
 	      *tmp++ = 32;
-	      ip_ll = ipa_or(ipa_build(0xfe80,0,0,0), ipa_and(ip, ipa_build(0,0,~0,~0)));
 	      ipa_hton(ip);
 	      memcpy(tmp, &ip, 16);
 	      ipa_hton(ip_ll);