From: Ondrej Zajicek (work) <santiago@crfreenet.org>
Date: Wed, 19 Dec 2018 17:10:39 +0000 (+0100)
Subject: IO: Workaround for broken FreeBSD behavior
X-Git-Tag: v1.6.5~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=04edf8f2f251f0c2a133843b898cad84f9312880;p=thirdparty%2Fbird.git

IO: Workaround for broken FreeBSD behavior

FreeBSD silently changes TTL to 1 when MSG_DONTROUTE is used, even when
it is explicitly set to another value. That breaks TTL security sockets,
including BFD which always uses TTL 255. Bad FreeBSD!
---

diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index f7a9e29f0..a90ddffd7 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -1614,7 +1614,9 @@ sk_sendmsg(sock *s)
   };
 
 #ifdef CONFIG_DONTROUTE_UNICAST
-  if (ipa_is_ip4(s->daddr) && ip4_is_unicast(ipa_to_ip4(s->daddr)))
+  /* FreeBSD silently changes TTL to 1 when MSG_DONTROUTE is used, therefore we
+     cannot use it for other cases (e.g. when TTL security is used). */
+  if (ipa_is_ip4(s->daddr) && ip4_is_unicast(ipa_to_ip4(s->daddr)) && (s->ttl == 1))
     flags = MSG_DONTROUTE;
 #endif