ipv4_hdr = l3_hdr;
*l4_proto = ipv4_hdr->next_proto_id;
m->l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
*l4_hdr = (char *)l3_hdr + m->l3_len;
m->ol_flags |= PKT_TX_IPV4;
break;
ipv4_hdr = l3_hdr;
*l4_proto = ipv4_hdr->next_proto_id;
m->l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
*l4_hdr = (char *)l3_hdr + m->l3_len;
m->ol_flags |= PKT_TX_IPV4;
break;