From ec331acf48535211fb5b50c87e74bf1c8370283a Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Thu, 24 Oct 2019 17:47:45 +0200
Subject: [PATCH] BGP: Fix handling of transitive extended communities

Transitive extended communities should be removed on external sessions,
the old code them in all cases.

Thanks to Jean-Daniel Pauget for the original patch.
---
 proto/bgp/attrs.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index b8921363..9a4e12d2 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -717,13 +717,23 @@ bgp_decode_mp_unreach_nlri(struct bgp_parse_state *s, uint code UNUSED, uint fla
 static void
 bgp_export_ext_community(struct bgp_export_state *s, eattr *a)
 {
-  struct adata *ad = ec_set_del_nontrans(s->pool, a->u.ptr);
+  if (!s->proto->is_interior)
+  {
+    struct adata *ad = ec_set_del_nontrans(s->pool, a->u.ptr);
 
-  if (ad->length == 0)
-    UNSET(a);
+    if (ad->length == 0)
+      UNSET(a);
 
-  ec_set_sort_x(ad);
-  a->u.ptr = ad;
+    ec_set_sort_x(ad);
+    a->u.ptr = ad;
+  }
+  else
+  {
+    if (a->u.ptr->length == 0)
+      UNSET(a);
+
+    a->u.ptr = ec_set_sort(s->pool, a->u.ptr);
+  }
 }
 
 static void