Ref https://docs.rs/async-std/1.0.1/async_std/net/trait.ToSocketAddrs.html. From a glance it seems this is indeed accurate. Since the result type from ToSocketAddrs is opaque, we could probably change it to be similar to FromStream::from_stream without breaking anything.

@bandheight out of curiosity: what's your use case for implementing ToSocketAddrs?

I'd be okay with changing the return type of to_socket_addrs to Pin<Box<dyn Future>> here. Performance impact of the change would be effectively none.

@yoshuawuyts I implemented an enum type to represent multiple address types.

pub enum Address {
    /// IP Address
    SocketAddr(SocketAddr),
    /// Domain name address, eg. example.com:8080
    Domain(String, u16),
}

If this type implement the trait ToSocketAddrs, it will be passed directly to TcpListener::bind and other similar functions.

@bandheight does the following work for you?

async fn bind_socket(addr: Address) -> io::Result<TcpListener> {
    match addr {
        SocketAddr(addr) => TcpListener::bind(addr).await?,
        SocketAddr((addr, port) => TcpListener::bind((&*addr, port)).await?,
    }
}

If we don't already support ToSocketAddr for (String, u16) then we should add that!

@yoshuawuyts This code is worked.
And it is also my current solution, but I want to make my code look more neat and elegant.
So implement the trait ToSocketAddrs is probably the best solution.

pub struct DomainName(pub String, pub u16);

...
// implement Deserialize for DomainName
...

#[derive(Deserialize)]
pub enum Address {
    /// IP Address
    SocketAddr(SocketAddr),
    /// Domain name address, eg. example.com:8080
    Domain(DomainName),
}

#[derive(Deserialize)]
pub struct Config {
    pub addr: Address,
}

...
let config: Config = <deserialize from config file>;
...

// This is neat and elegant.
let listener = TcpListener::bind(config.addr);

I vote for it that support ToSocketAddr for (String, u16).

agreed with @bandheight, that'd be cleaner to implement ToSocketAddrs.

cf. use case:

• https://github.com/dizda/fast-socks5/blob/429d491364ca515f1d3d4ec0fefadb6c35e82bcf/src/util/target_addr.rs#L76
• https://github.com/dizda/fast-socks5/blob/429d491364ca515f1d3d4ec0fefadb6c35e82bcf/src/server.rs#L476

👍

Shadowsocks does it for a similar purpose, but with std::net::ToSocketAddrs.

cf. https://github.com/shadowsocks/shadowsocks-rust/blob/f4feba9fc1c8a968d90a592c5f4e86ffc6dd322b/src/relay/socks5.rs#L332