From 4c6ee53f31a7ac667bc597b0fe19b6365abad415 Mon Sep 17 00:00:00 2001 From: "Ondrej Zajicek (work)" Date: Fri, 28 Jan 2022 18:13:18 +0100 Subject: [PATCH] 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. --- proto/bgp/attrs.c | 12 ++++++++---- proto/bgp/packets.c | 2 +- 2 files changed, 9 insertions(+), 5 deletions(-) diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c index 968d7d2b..15713b63 100644 --- 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 9d21fd34..21052186 100644 --- 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));