Of course, SSDP uses only UDP, not TCP, that's why I hope, that I can use only UDP golang functions to achieve my effect. Now I am trying with something like:

data := []byte(`M-SEARCH * HTTP/1.1\r\nHOST: 239.255.255.250:1900\r\nMAN: "ssdp:discover"\r\nST: roku:ecp\r\n\r\n`)
        fmt.Printf("sending data: %s\n", string(data))

_, err = connection.WriteToUDP(data, addr)

but with no success for now...