Feat/P2P FFI Layer

[nipsysdev]

This PR is an attempt at implementing a C FFI library for Archivist.
I tried following the work that was done in the Logos Storage FFI layer.

This is still a WIP, here are some potential issues that I've identified and remain to be addressed:

Remaining issues to address:

1. Stack-allocated NodeServer stored in shared context pointer

File: library/archivist_context.nim:108

A local stack variable's address is stored in a shared context pointer. When the procedure exits, the stack frame is invalidated but the pointer remains, risking causing undefined behavior, crashes, or data corruption.

2. archivist_close missing logic

File: library/libarchivist.nim:183-191

The archivist_close function is essentially a no-op that only returns a success callback without performing any actual cleanup.

3. Missing implementation to query repo store

File: library/archivist_thread_requests/requests/node_storage_request.nim:120-133

The space() function returns hardcoded zero values for all storage metrics instead of querying the repository store.

4. Missing implementation to check block existence

File: library/archivist_thread_requests/requests/node_storage_request.nim:135-139

The hasLocalBlock() function always returns false regardless of whether the block exists.

5. Debug requests processing not implemented

File: library/archivist_thread_requests/requests/node_debug_request.nim

All 7 debug operations return stub responses instead of performing actual operations:

DEBUG - Returns hardcoded version "0.1.0" and status "running"
LOG_LEVEL - Only logs the request, doesn't change log level
CONNECTED_PEERS - Always returns "0"
CONNECTED_PEER_IDS - Always returns empty array
FIND_PEER - Validates input but returns empty JSON
PEER_INFO - Validates input but returns empty JSON
DISCONNECT - Validates input but returns "disconnected" without actual disconnection

6. Callback handling needs improvement for concurrency

File: library/archivist_thread_requests/archivist_thread_request.nim:52

Current limitations:

• SPSC Channel limitation prevents concurrent request submissions from multiple client threads
• Sequential processing of requests
• Potential race conditions for progress callbacks
• Immediate request cleanup risking use-after-free

7. Hardcoded archivist version and revision

File: library/archivist_thread_requests/requests/node_info_request.nim:20-22

Lines contain hardcoded values: archivistVersion = "0.1.0" and archivistRevision = "unknown".

TOML serialization issues

I had to manually implement TOML serialization as I wasn't able to leverage the existing toml_serialization library with custom readValue procedures.
See: (archivist/conf_serialization.nim)[https://github.com/nipsysdev/archivist-node/blob/a1098b2d55219f4779ea7664ab4dc9a09eb5fd83/archivist/conf_serialization.nim]

Test Suite Issues

The build commands work correclt,y but the test suites currently have runtime issues. Tests fail with SIGSEGV or hang indefinitely.

Running the tests

make test

make test-context      # Context lifecycle tests
make test-config       # Configuration tests
make test-version      # Version information tests
make test-p2p          # P2P operations tests
make test-storage      # Storage operations tests
make test-upload       # Upload operations tests
make test-download     # Download operations tests
make test-edge-cases   # Edge case tests