Set local address to bind a specific interface

[amunra]

I'm more or less looking for the equivalent of https://docs.rs/reqwest/latest/reqwest/struct.ClientBuilder.html#method.local_address

This is useful for cases where there are multiple NICs installed and one of them is preferred (e.g., because it supports kernel bypass).

Looking at the code in stream.rs it looks like this is the main area of the code:

        let stream = if proto.is_some() && Some(Proto::HTTP) != proto {
            connect_socks(
                unit,
                proxy.clone().unwrap(),
                connect_deadline,
                sock_addr,
                hostname,
                port,
                proto.unwrap(),
            )
        } else if let Some(timeout) = timeout {
            TcpStream::connect_timeout(&sock_addr, timeout)
        } else {
            TcpStream::connect(sock_addr)
        };

If I understand it correctly, the limiting factor here is that std::net::tcp::TcpStream doesn't (as far as I can tell) support binding before connecting.

In other words, this would require socket2.
Alternatively, I guess, it could be approached with a custom Connector trait.

Is this something that might make sense adding as a feature?

[algesten]

Hi @amunra!

Because we want to be lean, I don't see us relying on socket2. However a connector trait has been proposed in #518. One way forward would be to explore the issues in that PR.

[amunra]

Yeah, that makes sense. I'll think about this and see if I can come up with something that will cater for the multiple requirements in that PR's discussion.

I'll continue there and close this issue.