https://news.ycombinator.com/item?id=40879547

    async fn stun(
        server: SocketAddr,
        mut socket: impl Sink<(BindingRequest, SocketAddr), Error = color_eyre::Report>
            + Stream<Item = Result<(BindingResponse, SocketAddr), color_eyre::Report>>
            + Unpin
            + Send
            + 'static,
    ) -> Result<SocketAddr> {
        socket.send((BindingRequest, server)).await?;
        let (message, _server) = socket.next().await.ok_or_eyre("No response")??;
        Ok(message.address)
    }

Fully working code at https://gist.github.com/joshka/af299be87dbd1f64060e47227b577...