When rewriting community_writebuf() the handling of non-transitive

ext-communities was put into the wrong place in the loop finding
start, end and number of communities to dump. As a result the end
pointer for regular communities can point at an ext-community and
with that the COMMUNITY attribute written includes unexpected extra
bytes. This in turn causes the peer to send a NOTIFICATION error
and to terminate the session.

Fix for -portable issue #64 reported by Pier Carlo Chiodi (pierky)
OK tb@

diff --git a/usr.sbin/bgpd/rde_community.c b/usr.sbin/bgpd/rde_community.c
index d7a8717..803a374 100644 (file)
--- a/usr.sbin/bgpd/rde_community.c
+++ b/usr.sbin/bgpd/rde_community.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: rde_community.c,v 1.13 2023/07/12 14:45:43 claudio Exp $ */
+/*     $OpenBSD: rde_community.c,v 1.14 2023/10/10 14:36:28 claudio Exp $ */
 
 /*
  * Copyright (c) 2019 Claudio Jeker <claudio@openbsd.org>
@@ -556,10 +556,9 @@ community_writebuf(struct rde_community *comm, uint8_t type, int ebgp,
        start = -1;
        for (l = 0; l < comm->nentries; l++) {
                cp = &comm->communities[l];
-
-               if (ebgp && non_transitive_ext_community(cp))
-                       continue;
                if ((uint8_t)cp->flags == t) {
+                       if (ebgp && non_transitive_ext_community(cp))
+                               continue;
                        num++;
                        if (start == -1)
                                start = l;