Node.JS: migrate to node-ffi-rs

[TimoGlastra]

Similar to #52, but for Node.JS. There's quite some issues with legacy/outdated FFI dependencies in the current wrapper.

Node FFI RS seems more modern, and like a good replacement.

See openwallet-foundation/credo-ts#2317 (comment) for context and an example

[huketo]

I was working on creating a holder desktop app for Windows at my company and encountered an issue with the node-ffi-napi library. In our case, we resolved it by replacing the dependencies for anoncreds-nodejs and askar-nodejs with the koffi library. It also seems like node-ffi-rs would be a good choice.

[TimoGlastra]

Hi @huketo, we also considered Koffi, and that seemed like a good choice as well.

Is your implementation complete? Would you be willing to contribute your implementation based on koffi?

[huketo]

Hi @huketo, we also considered Koffi, and that seemed like a good choice as well.

Is your implementation complete? Would you be willing to contribute your implementation based on koffi?

I handled the FFI conversion for anoncreds-nodejs, and another team member was in charge of askar-nodejs. They are currently on leave, so I'll talk to them about it once they're back.

[TimoGlastra]

Great, thanks!

We'd also be very interested in a new Anoncreds wrapper!

[huketo]

This is my modified version of anoncreds-nodejs.

find it here: https://github.com/huketo/anoncreds-wrapper-javascript/tree/feat-koffi

I had to modify it in a hurry due to our development schedule, so the binding interface is currently hardcoded. Also, instead of properly assigning values to the output parameters, it extracts the output in a somewhat crude way, using const ret: [null] = [null].

function handleReturnPointer<Return>(ptr: [null]): Return {
  const value = ptr[0]
  return value as Return
}

While it's functional for now, I know this approach isn't ideal for long-term maintainability. I plan to improve it later, but it's difficult to allocate time for it at the moment.

[TimoGlastra]

Thanks for this @huketo, it seems like a great start.

Would you be willing to open this as a draft PR to the anoncred-wrapper-javascript repository, and add a todo list of things to be improved / changed? That way if you don't have time to allocate, we can asses what the effort would be from our side to get it completed.

[TimoGlastra]

Fixed by #72, although using Koffi and not napi-ffi

@huketo, I think the approach in Askar is very similar to your PR. There are some differences (I think it's not needed to do koffi.alloc in most cases, as Koffi will handle it).