Bluetooth RFCOMM socket with Golang - sockets

Question

I'm trying to open an RFCOMM socket from Go. I have a test setup where the client connects to an echo server. The part that I'm stuck on is setting up the Bluetooth address. In C you have str2ba, which converts the MAC string to a byte array of six elements. In Go it appears it expects the device to be a uint16. I'm not sure how this would work.
package main
import (
"fmt"
"log"
"syscall"
"golang.org/x/sys/unix"
)
func main() {
fd, err := unix.Socket(syscall.AF_BLUETOOTH, syscall.SOCK_STREAM, unix.BTPROTO_RFCOMM)
if err != nil {
log.Fatalf("%v\n", err)
}
addr := unix.SockaddrHCI{Dev: 1, Channel: 1}
unix.Connect(fd, addr)
unix.Write(fd, []byte("Hello"))
var data []byte
unix.Read(fd, data)
fmt.Printf("Received: %v\n", string(data))
}
The Dev member in unix.SockaddrHCI is a uint16 and I think this is to represent the Bluetooth MAC. Is this correct?
Thanks.

Answer 1

I think that topicstarter already doesn't need this answer, but I needed it yesterday )) Kinda found right answer, so let me share the code that worked in my case (it was a HC06 bluetooth module for Arduino). I assume that module already was bt discovered and paired (e.g by means of bluetoothctl).
package main
import (
"strconv"
"strings"
"syscall"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
func main() {
mac := str2ba("00:19:10:08:FE:08") // YOUR BLUETOOTH MAC ADDRESS HERE
fd, err := unix.Socket(syscall.AF_BLUETOOTH, syscall.SOCK_STREAM, unix.BTPROTO_RFCOMM)
check(err)
addr := &unix.SockaddrRFCOMM{Addr: mac, Channel: 1}
var data = make([]byte, 50)
logrus.Print("connecting...")
err = unix.Connect(fd, addr)
check(err)
defer unix.Close(fd)
logrus.Println("done")
for {
n, err := unix.Read(fd, data)
check(err)
if n > 0 {
logrus.Infof("Received: %v\n", string(data[:n]))
}
}
}
func check(err error) {
if err != nil {
logrus.Fatal(err)
}
}
// str2ba converts MAC address string representation to little-endian byte array
func str2ba(addr string) [6]byte {
a := strings.Split(addr, ":")
var b [6]byte
for i, tmp := range a {
u, _ := strconv.ParseUint(tmp, 16, 8)
b[len(b)-1-i] = byte(u)
}
return b
}