From 65740e1bafa7875a3a667e18836bfb2985da1918 Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Tue, 19 May 2015 18:04:03 -0700
Subject: [PATCH] Don't register link local addresses for Next Hop Tracking.

We don't use the ifindex in registering NHT, and that may need to be
eventually fixed. But for now, ignore requests to register link local
addresses.
---
 bgpd/bgp_fsm.c | 10 ++++++++--
 bgpd/bgp_nht.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/bgpd/bgp_fsm.c b/bgpd/bgp_fsm.c
index faa171d294..3c33fc5423 100644
--- a/bgpd/bgp_fsm.c
+++ b/bgpd/bgp_fsm.c
@@ -1251,8 +1251,14 @@ bgp_start (struct peer *peer)
   if ((peer->ttl == 1) || (peer->gtsm_hops == 1))
     connected = 1;
 
-  bgp_find_or_add_nexthop(peer->bgp, family2afi(peer->su.sa.sa_family),
-                          NULL, peer, connected);
+  if (!bgp_find_or_add_nexthop(peer->bgp, family2afi(peer->su.sa.sa_family),
+			       NULL, peer, connected))
+    {
+      if (bgp_debug_neighbor_events(peer))
+	zlog_debug ("%s [FSM] Unable to register peer addr for NHT", peer->host);
+      return 0;
+    }
+
   status = bgp_connect (peer);
 
   switch (status)
diff --git a/bgpd/bgp_nht.c b/bgpd/bgp_nht.c
index 26a52e5635..ad9518e55b 100644
--- a/bgpd/bgp_nht.c
+++ b/bgpd/bgp_nht.c
@@ -98,6 +98,7 @@ bgp_find_or_add_nexthop (struct bgp *bgp, afi_t afi, struct bgp_info *ri,
 
   if (ri)
     {
+      /* This will return TRUE if the global IPv6 NH is a link local addr */
       if (make_prefix(afi, ri, &p) < 0)
 	return 1;
     }
@@ -114,8 +115,23 @@ bgp_find_or_add_nexthop (struct bgp *bgp, afi_t afi, struct bgp_info *ri,
 	  p.family = AF_INET6;
 	  p.prefixlen = IPV6_MAX_BITLEN;
 	  p.u.prefix6 = peer->su.sin6.sin6_addr;
+
+	  /* Don't register link local NH */
+	  if (IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6))
+	    return 1;
+	}
+      else
+	{
+	  if (BGP_DEBUG(nht, NHT))
+	    {
+	      zlog_debug("%s: Attempting to register with unknown AFI %d (not %d or %d)",
+			 __FUNCTION__, afi, AFI_IP, AFI_IP6);
+	    }
+	  return 0;
 	}
     }
+  else
+    return 0;
 
   rn = bgp_node_get (bgp_nexthop_cache_table[afi], &p);
 
@@ -165,6 +181,9 @@ bgp_delete_connected_nexthop (afi_t afi, struct peer *peer)
   struct bgp_nexthop_cache *bnc;
   struct prefix p;
 
+  if (!peer)
+    return;
+
   if (afi == AFI_IP)
     {
       p.family = AF_INET;
@@ -176,7 +195,13 @@ bgp_delete_connected_nexthop (afi_t afi, struct peer *peer)
       p.family = AF_INET6;
       p.prefixlen = IPV6_MAX_BITLEN;
       p.u.prefix6 = peer->su.sin6.sin6_addr;
+
+      /* We don't register link local address for NHT */
+      if (IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6))
+	return;
     }
+  else
+    return;
 
   rn = bgp_node_lookup(bgp_nexthop_cache_table[family2afi(p.family)], &p);
   if (!rn || !rn->info)
@@ -372,6 +397,7 @@ make_prefix (int afi, struct bgp_info *ri, struct prefix *p)
       break;
 #ifdef HAVE_IPV6
     case AFI_IP6:
+      /* We don't register link local NH */
       if (ri->attr->extra->mp_nexthop_len != BGP_ATTR_NHLEN_IPV6_GLOBAL
 	  || IN6_IS_ADDR_LINKLOCAL (&ri->attr->extra->mp_nexthop_global))
 	return -1;
@@ -382,6 +408,11 @@ make_prefix (int afi, struct bgp_info *ri, struct prefix *p)
       break;
 #endif
     default:
+      if (BGP_DEBUG(nht, NHT))
+	{
+	  zlog_debug("%s: Attempting to make prefix with unknown AFI %d (not %d or %d)",
+		     __FUNCTION__, afi, AFI_IP, AFI_IP6);
+	}
       break;
     }
   return 0;
-- 
2.39.5