peer.go
func isEphemeralHostPort(hostPort string) bool {
	return hostPort == "" || hostPort == ephemeralHostPort || strings.HasSuffix(hostPort, ":0")
}
func isEphemeralHostPort(hostPort string) bool {
	return hostPort == "" || hostPort == ephemeralHostPort || strings.HasSuffix(hostPort, ":0")
}
// isEphemeralHostPort returns if hostPort is the default ephemeral hostPort.