PF_PA_IFNAME
snl_add_msg_attr_string(nw, PF_PA_IFNAME, pa->ifname);
{ .type = PF_PA_IFNAME, .off = _OUT(ifname), .arg_u32 = IFNAMSIZ, .cb = snl_attr_copy_string },
nlattr_add_string(nw, PF_PA_IFNAME, a->ifname);
{ .type = PF_PA_IFNAME, .off = _OUT(ifname), .arg = (void *)IFNAMSIZ, .cb = nlattr_get_chara },