1. I have written a client in Node.js using the modules ffi-napi, ref-napi, and ref-struct (works fine)
2. The client calls C shared lib (.so) extension (works fine)
3. Example implementations (server.c and client.c) is available for reference, we need only client.c to replicate
4. You need to use Ubuntu (you can use 16.04 LTS or 18.04 LTS, I am suing the latter) and install the pre-req C projects (there are 3) to run everything successfully. I will guide you on this.
4. The C library needs to call some callbacks (pointer functions of a Struct) where I am stuck i.e. some functions require to send return values and some just receive arguments (data).
Point 4 needs to be debugged and should work perfectly. We can discuss in detail after contact. The person should be expert in C and Node.js (specially the modules mentioned).
Max 1 week