[PATCH] tun: openbsd: Don't change MTU when it's already the expected size

[Michael Zeltner]

Allows for running wireguard-go as non-root user
---
 tun/tun_openbsd.go | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tun/tun_openbsd.go b/tun/tun_openbsd.go
index 1e6191f..bdca231 100644
--- a/tun/tun_openbsd.go
+++ b/tun/tun_openbsd.go
@@ -173,12 +173,21 @@ func CreateTUNFromFile(file *os.File, mtu int) (Device, error) {
 
 	go tun.routineRouteListener(tunIfindex)
 
-	err = tun.setMTU(mtu)
+	var cur_mtu int
+	cur_mtu, err = tun.MTU()
 	if err != nil {
 		tun.Close()
 		return nil, err
 	}
 
+	if cur_mtu != mtu {
+		err = tun.setMTU(mtu)
+		if err != nil {
+			tun.Close()
+			return nil, err
+		}
+	}
+
 	return tun, nil
 }
 
-- 
2.21.0