Nimbus verified proxy integration

[vitvly]

Work has been ongoing for a while on integrating Nimbus verified proxy (nimbus-verified-proxy) client into status-go.

What is nimbus-verified-proxy?

This is an RPC proxy server which is part of nimbus-eth1 project. It can verify e.g. eth_getBalance responses that we receive from Infura or other third-party provider, by verifying cryptographic proofs obtained from Nimbus consensus client.

More detail here: https://notes.status.im/nimbus-light-proxy

Overview of integration with status-go

The project consists of several parts:

1. nimbus-eth1 changes.
2. Small Golang wrapper library for nimbus-verified-proxy.
3. status-go changes.
4. Client updates to the build process (both Nix scripts for status-mobile and Makefiles for status-desktop)

1. nimbus-eth1 changes

• Add Makefile targets to build nimbus-verified-proxy as a [static-lib, dynamic-lib, unlinked-objs].
  Currently dynamic-lib and unlinked-objs targets work properly. Static lib builds are not working on macOS due to system's ar tool not processing linkerArgs.txt files (more detail here: Static linking problems on macOS nimbus-eth1#1500)
• Modify nimbus-verified-proxy code to accept external C callbacks and JSON configuration instead of cmd-line parameters

Tinkered a bit with various GC settings, separate issue here: status-im/nimbus-eth1#1501.

PR: status-im/nimbus-eth1#1572

2. Golang wrapper library

• Small Golang library wrapping nimbus-verified-proxy, that starts the proxy from within Go, optionally passing [optimistic,finalized]HeaderCallbacks. Repo: https://github.com/siphiuel/lc-proxy-wrapper

3. status-go changes

• PR adding eth_getBalance handling via proxy, optionally enabled via a build tag: nimbus-verified-proxy integration #3281

4. Client updates

• status-mobile Nix build. PR: [WIP] nimbus-light-proxy integration status-mobile#15341
  Nix can build nimbus-verified-proxy and status-go fine, however gomobile cannot bundle extra shared library files into AAR/Framework files
• status-desktop build. WIP

Current status

Rebased with Nim 1.6 changes in nimbus-eth1, working on:

• trying to use unlinked-objs inside lc-proxy-wrapper, as static/dynamic lib approaches are problematic
• status-desktop build changes

[Samyoul]

Wow @siphiuel this is looking very exciting! I'm really looking forward to seeing the results of all you work on this.