xdp: add missing Ethernet header in socket->frame_limit calculation from MTU

diff --git a/src/libknot/xdp/xdp.c b/src/libknot/xdp/xdp.c
index 214675a8dd4811ec79a14f914e499933edcc33f4..5dbc5d935d1df76d037de05b927e1dd4bee5cb40 100644 (file)
--- a/src/libknot/xdp/xdp.c
+++ b/src/libknot/xdp/xdp.c
@@ -234,8 +234,8 @@ int knot_xdp_init(knot_xdp_socket_t **socket, const char *if_name, int if_queue,
 
        (*socket)->frame_limit = FRAME_SIZE;
        ret = knot_eth_mtu(if_name);
-       if (ret > 0) {
-               (*socket)->frame_limit = MIN((unsigned)ret, (*socket)->frame_limit);
+       if (ret > 0) { // Note: VLAN header isn't considered for simplicity.
+               (*socket)->frame_limit = MIN(sizeof(struct ethhdr) + ret, (*socket)->frame_limit);
        }
 
        if (flags & KNOT_XDP_FILTER_ROUTE) {