From 32a3b737c688653ed1bf72bda187b7a17148be27 Mon Sep 17 00:00:00 2001
From: jmatthew <jmatthew@openbsd.org>
Date: Tue, 24 Oct 2023 09:13:22 +0000
Subject: [PATCH] Delete any existing v4 address before setting a new one. 
 This allows us to keep a working default route when the address changes.

ok dlg@ kn@
---
 sys/dev/usb/if_umb.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sys/dev/usb/if_umb.c b/sys/dev/usb/if_umb.c
index 46ecb684241..0d0c2c4716f 100644
--- a/sys/dev/usb/if_umb.c
+++ b/sys/dev/usb/if_umb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_umb.c,v 1.55 2023/09/01 20:24:29 mvs Exp $ */
+/*	$OpenBSD: if_umb.c,v 1.56 2023/10/24 09:13:22 jmatthew Exp $ */
 
 /*
  * Copyright (c) 2016 genua mbH
@@ -1814,6 +1814,14 @@ umb_add_inet_config(struct umb_softc *sc, struct in_addr ip, u_int prefixlen,
 	struct rtentry *rt;
 	int	 rv;
 
+	memset(&ifra, 0, sizeof (ifra));
+	rv = in_ioctl(SIOCDIFADDR, (caddr_t)&ifra, ifp, 1);
+	if (rv != 0 && rv != EADDRNOTAVAIL) {
+		printf("%s: unable to delete IPv4 address, error %d\n",
+		    DEVNAM(ifp->if_softc), rv);
+		return rv;
+	}
+
 	memset(&ifra, 0, sizeof (ifra));
 	sin = &ifra.ifra_addr;
 	sin->sin_family = AF_INET;
-- 
2.20.1