func (p *Proxy) newConn(clientAddr *net.UDPAddr) (*Conn, error) {
	p.mutex.Lock()
	defer p.mutex.Unlock() // Simpler locking handling, also safer access since we are locking not
	//  only the map, but also conn.ServeConn and conn.ClientAddr.
	conn, ok := p.connMap[clientAddr.String()]
	if !ok {
		conn = &Conn{
			clientAddr: clientAddr,
		}
		addr, err := net.ResolveUDPAddr("udp", net.JoinHostPort(p.config.TargetHost, p.config.TargetPort))
		if err != nil {
			return nil, err
		}
		t, err := net.DialUDP("udp", nil, addr)
		if err != nil {
			return nil, err
		}
		conn.serverConn = t
		p.connMap[clientAddr.String()] = conn
	}
	return conn, nil
}