NPChat — Hybrid C++/Svelte WebRTC Chat

A real-time chat and video-calling application with a C++23 backend and a Svelte 5 + TypeScript frontend. It uses a custom NPRPC framework for typed RPC between client and server, SQLite for persistence, and WebRTC for peer-to-peer media.

Features

• Secure login with cookie-based sessions and CSRF protection
• Chats, contacts, messages, unread tracking
• Real-time notifications via observer pattern
• WebRTC video calls with trickle ICE and TURN support
• Custom IDL (.npidl) → generated client/server RPC stubs
• Optimized hybrid build (CMake/Docker for C++, Vite for client)

Tech Stack

• Backend: C++23, CMake, SQLite, OpenSSL, spdlog
• Frontend: Svelte 5, TypeScript, Vite, Tailwind CSS
• RPC: NPRPC (custom), IDL in idl/
• Media: WebRTC (STUN/TURN)

Repository Layout

• server/ — C++ server and services
• client/ — Svelte 5 frontend
• idl/ — NPRPC IDL files (generate TS/CPP bindings)
• external/ — NPSystem/NPRPC sources
• build.sh, configure.sh — Build scripts (hybrid)
• gen_stubs.sh — Generate RPC stubs and copy to client

Quick Start

Prerequisites

• Linux host (tested), C++ toolchain, CMake
• Node.js 18+ and npm
• OpenSSL (for TLS if using HTTPS/WSS)

Setup

• Configure once
  • ./configure.sh
• Build all (server + client)
  • ./build.sh
• Run backend server
  • ./build.sh run
• Frontend dev server (in another terminal)
  • cd client && npm run dev

The client dev server runs with HTTPS (see client/vite.config.ts) and proxies RPC/WebSocket to the C++ backend.

Environment Variables

Server (.env in repo root)

• USE_SSL=1 — enable TLS (default in this repo)
• BUILD_TYPE=Debug|Release

Client (client/.env.* for Vite)

• Preferred (JSON array of ICE servers)
  • VITE_WEBRTC_ICE_SERVERS='[{"urls":"stun:stun.l.google.com:19302"},{"urls":"turn:example.com:3478","username":"user","credential":"pass"}]'
• Fallback (individual vars)
  • VITE_WEBRTC_STUN_URLS=stun:stun.l.google.com:19302,stun:stun1.l.google.com:19302
  • VITE_WEBRTC_TURN_URL=turn:example.com:3478
  • VITE_WEBRTC_TURN_USERNAME=user
  • VITE_WEBRTC_TURN_CREDENTIAL=pass

Notes

• Vite only exposes variables prefixed with VITE_ to client code.
• See client/.env.example for examples.

Development Workflow

• Generate RPC stubs after updating idl/npchat.npidl:
  • ./gen_stubs.sh
• Incremental rebuilds:
  • ./build.sh server (backend only)
  • ./build.sh client (frontend bundle only)
• Hot reload for UI:
  • cd client && npm run dev

WebRTC Testing

• Open the app in two browser tabs or devices
• Start a call from a chat using the “Call” button
• ICE trickling and end-of-candidates are handled automatically
• Ensure your ICE/TURN config is set via Vite env for NAT traversal

Deployment

• Docker build and packaging scripts included:
  • ./01_docker_build.sh — Build production images
  • ./02_pack_runtime.sh — Create runtime package
  • ./03_deploy.sh — Deploy to remote host

Adjust server certificates and hostnames in client/vite.config.ts and server config as needed.

Security

• Cookie-based sessions with CSRF protection
• 256-bit cryptographically secure session IDs (OpenSSL)
• Authorization checks for chat operations (creator permissions)

License

This project is licensed under the MIT License. See LICENSE.

Acknowledgements

• NPSystem / NPRPC framework (in external/)
• spdlog, Tailwind CSS, Svelte, Vite