u32 tcp_cksum = b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
u32 udp_cksum = b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
int is_ip4 = b->flags & VNET_BUFFER_F_IS_IP4;
u32 tcp_cksum = b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
u32 udp_cksum = b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
int is_ip4 = b->flags & VNET_BUFFER_F_IS_IP4;