func getReflexive(sock *net.UDPConn) (*net.UDPAddr, error) {
serverAddr, err := net.ResolveUDPAddr("udp", *stunserver)
if err != nil {
return nil, errors.New("Couldn't resolve STUN server")
}
var tid [12]byte
if _, err = rand.Read(tid[:]); err != nil {
return nil, err
}
request, err := stun.BindRequest(tid[:], nil, true, false)
if err != nil {
return nil, err
}
n, err := sock.WriteTo(request, serverAddr)
if err != nil {
return nil, err
}
if n < len(request) {
return nil, err
}
var buf [1024]byte
n, _, err = sock.ReadFromUDP(buf[:])
if err != nil {
return nil, err
}
packet, err := stun.ParsePacket(buf[:n], nil)
if err != nil {
return nil, err
}
if packet.Class != stun.ClassSuccess || packet.Method != stun.MethodBinding || packet.Addr == nil || !bytes.Equal(tid[:], packet.Tid[:]) {
return nil, errors.New("No address provided by STUN server")
}
return packet.Addr, nil
}
func (e *attemptEngine) xmit() (time.Time, error) {
now := time.Now()
var ret time.Time
var err error
for i := range e.attempts {
if e.attempts[i].timeout.Before(now) {
e.attempts[i].timeout = time.Now().Add(probeTimeout)
e.attempts[i].tid, err = stun.RandomTid()
if err != nil {
return time.Time{}, err
}
packet, err := stun.BindRequest(e.attempts[i].tid, nil, false, e.attempts[i].chosen)
if err != nil {
return time.Time{}, err
}
e.sock.WriteToUDP(packet, e.attempts[i].Addr)
}
if ret.IsZero() || e.attempts[i].timeout.Before(ret) {
ret = e.attempts[i].timeout
}
}
return ret, nil
}