Using `0.0.0.0` as the IP address for server binding results in an extremely slow/broken connection

[Frontear]

Problem:

Most of the s2n-quic examples in this repository bind their socket to 127.0.0.1:4433. If we instead use 0.0.0.0:<PORT>, the connection seems to either be extremely slow or does not work at all. Using the exact same port with 127.0.0.1 instead will make it work flawlessly.

Reproduction Steps

Running the provided code will fail with "MaxHandshakeDurationExceeded". Changing the server IP from 0.0.0.0 to 127.0.0.1 will immediately make the connection and cleanly terminate.

use std::error::Error;
use std::net::SocketAddr;

use s2n_quic::{ Client, Server };
use s2n_quic::client::Connect;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
  let server = Server::builder()
    .with_tls((CERT, KEY))? // FIXME: add this yourself
    .with_io("0.0.0.0:25575")? // WARN: change to `127.0.0.1`
    .start()?;

  let client = Client::builder()
    .with_tls(CERT)? // FIXME: add this yourself
    .with_io("0.0.0.0:0")?
    .start()?;

  let connect = Connect::new("0.0.0.0:25575".parse::<SocketAddr>()?) // WARN: change to `127.0.0.1`
    .with_server_name("localhost");
  let conn = client.connect(connect).await?;

  return Ok(());
}

[boquan-fang]

Hello @Frontear,

Thanks for cutting the issue to us!

By the look at your code, the server doesn't seem to accept any connections. To properly start the server, you should call server.accept().

I believe the input to the Connect::new() method has to be a concrete value, which is 127.0.0.1 in your use case.

Furthermore, we have a debugging guide and some steps for you to find out more information:

• Enable the tracing event provider, along with a tracing-subscriber that writes logs to stdout
• Enable keylogging in the TLS provider: https://docs.rs/s2n-quic/latest/s2n_quic/provider/tls/default/client/struct.Builder.html#method.with_key_logging. You'll also need to set the SSLKEYLOG environment variable
• Record a pcap of the traffic. If you can, it would make it easier to use if the TLS secrets are embedded in the pcap file: https://my.f5.com/manage/s/article/K42350941

Please let us know if you have any more questions.