Fix the failure to create UdpSocket asynchronously due to immediate polling

[mokeyish]

Fix the failure to create UdpSocket asynchronously due to immediate polling

[djc]

I think this needs a little more context. What behavior did you see, and why do you think it is wrong?

[mokeyish]

@djc Hi,

I implement the trait RuntimeProvider to support for querying over socks5. But current code will never execute the code after await. This PR sovles the problem.

https://github.com/hickory-dns/hickory-dns/blob/main/crates/resolver/src/name_server/connection_provider.rs#L92

  fn bind_udp(
      &self,
      local_addr: SocketAddr,
      server_addr: SocketAddr,
  ) -> Pin<Box<dyn Send + Future<Output = io::Result<Self::Udp>>>> {
      let proxy = self.proxy.clone();
      Box::pin(async move {
            let backing_socket = TokioTcpStream::connect(proxy.server).await;
            /// 👉 The code below never executes
            let backing_socket = match backing_socket {
                Ok(s) => s,
                Err(err) => {
                    panic!("{:?}", err);
                },
            };
            ...
      })
  }

[bluejekyll]

Sorry, I'm actually confused about how this change resolves the issue you're mentioning. I see that you're fixing the kind of ugly delay and awake code in here that exists today.

Is this comment what this is resolving?:

                // TODO: this immediate poll might be wrong in some cases...
                match (*self.closure)(bind_addr, self.name_server)
                    .as_mut()
                    .poll(cx)
                {

It looks like with this change we will always return on the poll of the socket, which is good, but it is removing the QOS that was in place with the for loop that was limited to the 10 iterations on finding a port. If that fails in 10 iterations, we'd return to allow other futures to make progress. This appears to not have a QOS limit on the number of attempts, and could mean that an application could get deadlocked on this trying to find an unused port. Am I missing that?