func NewTCPRawRelay(dests []string) (Relay, error) {
	return newTCPRelay(dests, func(_ bool, src, dst net.Conn) {
		io.Copy(src, dst)
	})
}
func NewTCPRawRelay(dests []string) (Relay, error) {
	return newTCPRelay(dests, func(_ bool, src, dst net.Conn) {
		io.Copy(src, dst)
	})
}
// NewTCPRawRelay creates a relay that just pipes data from one connection
// to another directly.