WASI: asynchronous name resolution APIs

[npmccallum]

One of the greatest flaws of current *nix APIs is its complete lack of async DNS. We also need native support for encrypted DNS. This should be one of the highest priorities on the "things to fix" list.

[sunfishcode]

Following up on my coment in #69, my impression is that the best way to go here might be to start thinking in terms of creating a Network module, separate from the Core module. Core can just focus on relatively generic stream/datagram operations, and Network can be the place where we do DNS, create sockets, and so on.

If that makes sense, it'd be good to start making a rough list of features that the Network module should aim to include.

[npmccallum]

I think that's sane.

Regarding DNS, we can also choose not to offer APIs. We can just depend on libraries to do this lifting for us. But if we do provide name resolution, it need to be async.

Honestly, I'd love to see a SOCK_DNS socket type for name resolution. You push a struct into the socket and poll() to wait for the reply.

However, and I'm afraid I might be harping on this, I'd really like to keep the core module very small. With versioning (#74), we can always expand it and even break the ABI. But, IMHO, core should only be a set of ABIs that all other modules depend on. I don't think there is any requirement for core to be functional by itself.

[badeend]

wasi-sockets has an asynchronous resolver .

The interface itself is pretty simple and leaves it up to the implementation to pick the most appropriate resolver strategy. (Hostfile, DNS, DNS-over-HTTPS, ...)

Anyway, I think this issue can be closed now. Any further discussion (if any) can take place at https://github.com/WebAssembly/wasi-sockets