Add mtu6 option to override IPv6 MTU

[project/netifd.git] / interface-ip.c

diff --git a/interface-ip.c b/interface-ip.c
index aec3892..7f8a451 100644 (file)
--- a/interface-ip.c
+++ b/interface-ip.c
@@ -767,10 +767,11 @@ interface_set_prefix_address(struct device_prefix_assignment *assignment,
                route.metric = iface->metric;
                system_add_route(l3_downlink, &route);
 
-               if (uplink && uplink->l3_dev.dev) {
-                       int mtu = system_update_ipv6_mtu(
-                                       uplink->l3_dev.dev, 0);
-                       if (mtu > 0)
+               if (uplink && uplink->l3_dev.dev && !(l3_downlink->settings.flags & DEV_OPT_MTU6)) {
+                       int mtu = system_update_ipv6_mtu(uplink->l3_dev.dev, 0);
+                       int mtu_old = system_update_ipv6_mtu(l3_downlink, 0);
+
+                       if (mtu > 0 && mtu_old > mtu)
                                system_update_ipv6_mtu(l3_downlink, mtu);
                }