if addr == nil {
		return 0, 0, errMissingAddress
	}
	sa, err := addr.sockaddr(c.fd.family)
	if err != nil {
		return 0, 0, err
	}
	return c.fd.writeMsg(b, oob, sa)
}

func (sd *sysDialer) dialIP(ctx context.Context, laddr, raddr *IPAddr) (*IPConn, error) {
	network, proto, err := parseNetwork(ctx, sd.network, true)
	if err != nil {
		return nil, err
	}
	switch network {
	case "ip", "ip4", "ip6":