BGP: Make routing loops silent

One of previous commits added error logging of invalid routes. This
also inadvertently caused error logging of route loops, which should
be ignored silently. Fix that.

diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index 968d7d2b596965efba858d363c9d60dd451f519f..15713b634ed5531afc92786aa189c6c214bd8c81 100644 (file)
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -1397,19 +1397,19 @@ bgp_decode_attrs(struct bgp_parse_state *s, byte *data, uint len)
 
   /* Reject routes with our ASN in AS_PATH attribute */
   if (bgp_as_path_loopy(p, attrs, p->local_as))
-    goto withdraw;
+    goto loop;
 
   /* Reject routes with our Confederation ID in AS_PATH attribute; RFC 5065 4.0 */
   if ((p->public_as != p->local_as) && bgp_as_path_loopy(p, attrs, p->public_as))
-    goto withdraw;
+    goto loop;
 
   /* Reject routes with our Router ID in ORIGINATOR_ID attribute; RFC 4456 8 */
   if (p->is_internal && bgp_originator_id_loopy(p, attrs))
-    goto withdraw;
+    goto loop;
 
   /* Reject routes with our Cluster ID in CLUSTER_LIST attribute; RFC 4456 8 */
   if (p->rr_client && bgp_cluster_list_loopy(p, attrs))
-    goto withdraw;
+    goto loop;
 
   /* If there is no local preference, define one */
   if (!BIT32_TEST(s->attrs_seen, BA_LOCAL_PREF))
@@ -1430,6 +1430,10 @@ withdraw:
 
   s->err_withdraw = 1;
   return NULL;
+
+loop:
+  /* Loops are handled as withdraws, but ignored silently. Do not set err_withdraw. */
+  return NULL;
 }
 
 void

diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index 9d21fd34f2d04cd0385b06ebb40c3d983c227ce1..21052186801ad5cebc0725e9ebe9236316f12567 100644 (file)
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1422,7 +1422,7 @@ bgp_decode_mpls_labels(struct bgp_parse_state *s, byte **pos, uint *len, uint *p
 
     /* RFC 8277 2.4 - withdraw does not have variable-size MPLS stack but
        fixed-size 24-bit Compatibility field, which MUST be ignored */
-    if (!a && !s->err_withdraw)
+    if (!s->reach_nlri_step)
       return;
   }
   while (!(label & BGP_MPLS_BOS));