drivers/espat/tcp.go

package espat

import (
	"errors"
	"strconv"
	"strings"
)

const (
	TCPMuxSingle   = 0
	TCPMuxMultiple = 1

	TCPTransferModeNormal      = 0
	TCPTransferModeUnvarnished = 1
)

// GetDNS returns the IP address for a domain name.
func (d *Device) GetDNS(domain string) (string, error) {
	d.Set(TCPDNSLookup, "\""+domain+"\"")
	r := strings.Split(string(d.Response(1000)), ":")
	if len(r) != 2 {
		return "", errors.New("Invalid domain lookup result")
	}
	res := strings.Split(r[1], "\r\n")
	return res[0], nil
}

// ConnectTCPSocket creates a new TCP socket connection for the ESP8266/ESP32.
// Currently only supports single connection mode.
func (d *Device) ConnectTCPSocket(addr, port string) error {
	protocol := "TCP"
	val := "\"" + protocol + "\",\"" + addr + "\"," + port + ",120"
	d.Set(TCPConnect, val)
	r := d.Response(1000)
	if strings.Contains(string(r), "OK") {
		return nil
	}
	return errors.New("ConnectTCPSocket error:" + string(r))
}

// ConnectUDPSocket creates a new UDP connection for the ESP8266/ESP32.
func (d *Device) ConnectUDPSocket(addr, sendport, listenport string) error {
	protocol := "UDP"
	val := "\"" + protocol + "\",\"" + addr + "\"," + sendport + "," + listenport + ",2"
	d.Set(TCPConnect, val)
	r := d.Response(pause)
	if strings.Contains(string(r), "OK") {
		return nil
	}
	return errors.New("ConnectUDPSocket error:" + string(r))
}

// ConnectSSLSocket creates a new SSL socket connection for the ESP8266/ESP32.
// Currently only supports single connection mode.
func (d *Device) ConnectSSLSocket(addr, port string) error {
	protocol := "SSL"
	val := "\"" + protocol + "\",\"" + addr + "\"," + port + ",120"
	d.Set(TCPConnect, val)
	// this operation takes longer, so wait up to 6 seconds to complete.
	r := d.Response(6000)
	if strings.Contains(string(r), "CONNECT") {
		return nil
	}
	return errors.New("ConnectSSLSocket error:" + string(r))
}

// DisconnectSocket disconnects the ESP8266/ESP32 from the current TCP/UDP connection.
func (d *Device) DisconnectSocket() error {
	d.Execute(TCPClose)
	d.Response(pause)
	return nil
}

// SetMux sets the ESP8266/ESP32 current client TCP/UDP configuration for concurrent connections
// either single TCPMuxSingle or multiple TCPMuxMultiple (up to 4).
func (d *Device) SetMux(mode int) error {
	val := strconv.Itoa(mode)
	d.Set(TCPMultiple, val)
	d.Response(pause)
	return nil
}

// GetMux returns the ESP8266/ESP32 current client TCP/UDP configuration for concurrent connections.
func (d *Device) GetMux() ([]byte, error) {
	d.Query(TCPMultiple)
	return d.Response(pause), nil
}

// SetTCPTransferMode sets the ESP8266/ESP32 current client TCP/UDP transfer mode.
// Either TCPTransferModeNormal or TCPTransferModeUnvarnished.
func (d *Device) SetTCPTransferMode(mode int) error {
	val := strconv.Itoa(mode)
	d.Set(TransmissionMode, val)
	d.Response(pause)
	return nil
}

// GetTCPTransferMode returns the ESP8266/ESP32 current client TCP/UDP transfer mode.
func (d *Device) GetTCPTransferMode() []byte {
	d.Query(TransmissionMode)
	return d.Response(pause)
}

// StartSocketSend gets the ESP8266/ESP32 ready to receive TCP/UDP socket data.
func (d *Device) StartSocketSend(size int) error {
	val := strconv.Itoa(size)
	d.Set(TCPSend, val)

	// when ">" is received, it indicates
	// ready to receive data
	r := d.Response(pause)
	if strings.Contains(string(r), ">") {
		return nil
	}
	return errors.New("StartSocketSend error:" + string(r))
}

// EndSocketSend tell the ESP8266/ESP32 the TCP/UDP socket data sending is complete,
// and to return to command mode. This is only used in "unvarnished" raw mode.
func (d *Device) EndSocketSend() error {
	d.Write([]byte("+++"))

	d.Response(pause)
	return nil
}