ls-upnp - List of UPnP devices on your local network. Written by Go

main.go

package main

import (
	"fmt"
	"net"
	"os"
	"strings"
	"time"
)

func main() {
	if err := run(); err != nil {
		fmt.Fprintf(os.Stderr, "run failed: %q", err)
		os.Exit(1)
	}
}

var lines = []string{
	"M-SEARCH * HTTP/1.1",
	"HOST: 239.255.255.250:1900",
	"MAN: ssdp:discover",
	"MX: 5",
	"ST: ssdp:all",
	"",
	"",
}

func run() error {
	conn, err := net.ListenPacket("udp", ":0")
	if err != nil {
		return err
	}
	defer conn.Close()

	upnpAddr, err := net.ResolveUDPAddr("udp", "239.255.255.250:1900")
	if err != nil {
		return fmt.Errorf("failed to resolve upnp addr: %w", err)
	}

	_, err = conn.WriteTo([]byte(strings.Join(lines, "\r\n")), upnpAddr)
	if err != nil {
		return fmt.Errorf("failed to write request: %w", err)
	}

	data := make([]byte, 4096)
	for {
		conn.SetReadDeadline(time.Now().Add(3 * time.Second))

		n, remoteAddr, err := conn.ReadFrom(data)
		if err != nil {
			if os.IsTimeout(err) {
				return nil
			}
			return err
		}
		fmt.Println("<---------------", remoteAddr.String())
		fmt.Println(string(data[:n]))
	}
}

$ go run main.go

About UPnP > https://en.wikipedia.org/wiki/Universal_Plug_and_Play
About SSDP > https://en.wikipedia.org/wiki/Simple_Service_Discovery_Protocol
Japanese > https://www.buffalo.jp/support/faq/detail/13603.html