[PATCH] sysdep/bsd: propagate OS-level IFF_MULTICAST to internal IF_MULTICAST flag

Toke Høiland-Jørgensen toke at toke.dk
Mon Apr 19 22:26:53 UTC 2021

The BSD code did not propagate the OS-level IFF_MULTICAST flag to the
Bird-internal IF_MULTICAST flag, which causes problems with Wireguard
interfaces on FreeBSD. The Linux sysdep code does propagate the flag
already, so just copy over the same check and flag update.

Tested-by: Stefan Haller <stefan.haller at stha.de>
Signed-off-by: Toke Høiland-Jørgensen <toke at toke.dk>
 sysdep/bsd/krt-sock.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sysdep/bsd/krt-sock.c b/sysdep/bsd/krt-sock.c
index c2faa23dd44f..cd89544063c7 100644
--- a/sysdep/bsd/krt-sock.c
+++ b/sysdep/bsd/krt-sock.c
@@ -665,6 +665,9 @@ krt_read_ifinfo(struct ks_msg *msg, int scan)
     f.flags |= IF_MULTIACCESS;      /* NBMA */
+  if (fl & IFF_MULTICAST)
+    f.flags |= IF_MULTICAST;
   iface = if_update(&f);
   if (!scan)

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