From: Fabian Bläse <fabian@blaese.de>
Date: Tue, 10 Dec 2024 01:14:06 +0000 (+0100)
Subject: Babel: fix seqno wrapping on seqno request
X-Git-Tag: v2.17~70
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cfac0076fb7365fe91360fa351f311f141a7a303;p=thirdparty%2Fbird.git

Babel: fix seqno wrapping on seqno request

The Babel seqno wraps around when reaching its maximum value (UINT16_MAX).
When comparing seqnos, this has to be taken into account. Therefore,
plain number comparisons do not work.
---

diff --git a/proto/babel/babel.c b/proto/babel/babel.c
index fe5c0599a..b5cbb63f8 100644
--- a/proto/babel/babel.c
+++ b/proto/babel/babel.c
@@ -1015,7 +1015,7 @@ babel_send_update_(struct babel_iface *ifa, btime changed, struct fib *rtable)
 
     /* Our own seqno might have changed, in which case we update the routes we
        originate. */
-    if ((e->router_id == p->router_id) && (e->seqno < p->update_seqno))
+    if ((e->router_id == p->router_id) && gt_mod64k(p->update_seqno, e->seqno))
     {
       e->seqno = p->update_seqno;
       e->updated = current_time();