abstract namespace unix sockets fail in hostname lookup

[jayvdb]

According to https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS

If the host name starts with @, it is taken as a Unix-domain socket in the abstract namespace (currently supported on Linux and Windows).

However tokio-posgres connect prevents host=@... ; the error is

called Result::unwrap() on an Err value: Custom { kind: Uncategorized, error: "failed to lookup address information: Name or service not known" }

And the backtrace points to this line https://github.com/sfackler/rust-postgres/blob/02463b1/tokio-postgres/src/connect.rs#L98

[jayvdb]

Note tokio doesnt support this tokio-rs/tokio#4610

I was able to workaround this using the suggestions there, ending up with

           let socket = if path.display().to_string().starts_with('@') {
                // #[cfg(target_os = "linux")]
                let addr = SocketAddr::from_abstract_name(path.as_os_str().as_encoded_bytes()).unwrap();
                eprintln!("Connecting to abstract Unix socket: {addr:?}");
                let std_stream = std::os::unix::net::UnixStream::connect_addr(&addr).unwrap();
                let stream = UnixStream::from_std(std_stream.into());
                connect_with_timeout(async { stream }, connect_timeout).await.unwrap()
            }
            else {
                connect_with_timeout(UnixStream::connect(path), connect_timeout).await.unwrap()
            };

But then I get connection refused