taglinefilesource code
tosxor211net/ipv4/ip_fw.cunsigned char    tosand, tosxor;
tosxor497net/ipv4/ip_fw.ctosxor=f->fw_tosxor;
tosxor500net/ipv4/ip_fw.ctosxor=0x00;
tosxor506net/ipv4/ip_fw.cip->tos = (old_tos & tosand) ^ tosxor;