Architecture

The VPN Share Tool is split into a desktop client application and a discovery server registry.

High-Level Overview

The system consists of two primary applications:

  1. Client Application (vpn-share-tool): A desktop GUI application that users interact with to share URLs and view available services.
  2. Discovery Server (discovery): A central (or local) registry server that tracks active client instances and facilitates service discovery.
graph TD
    Client1[vpn-share-tool Client 1] -- TCP 45679 Registration --> Server[Discovery Server]
    Client2[vpn-share-tool Client 2] -- TCP 45679 Registration --> Server
    Browser[Admin Browser] -- HTTPS 8080 Dashboard --> Server

Key Components

1. Client Application (cmd/vpn-share-tool)

  • Role: The main user-facing tool. It acts as both a proxy server (forwarding traffic) and a client (consuming services).
  • Technology:
    • Go (Golang) for backend logic.
    • Fyne for the cross-platform desktop GUI (Windows, Linux, macOS).
  • Core Logic (core/):
    • Proxy Engine: Manages HTTP/HTTPS proxies. It can rewrite URLs and modify content (e.g., injecting scripts) to ensure proxied sites work correctly.
    • Local API Server: Each client starts a local HTTP server (defaulting to port 10081+) to handle internal commands and status updates.
    • Registration Manager: Automatically finds the Discovery Server on the network and registers the client's presence.
  • Web Interface:
    • Debug Dashboard (core/debug_web): A built-in web interface (Vue.js) for inspecting captured requests and debugging proxy traffic (HAR support).

2. Discovery Server (cmd/discovery)

  • Role: Maintains a registry of all active vpn-share-tool instances on the network.
  • Technology: Go.
  • Communication:
    • TCP (Port 45679): Custom protocol for client registration and heartbeats. Handles TLS encryption.
    • HTTP/HTTPS (Port 8080): Provides a web dashboard and API for viewing active instances and configuring global settings.
  • Web Interface:
    • Discovery Dashboard (discovery_web): A Vue.js-based admin panel to view active servers, shared proxies, and logs.

3. Build System (dev/)

  • Tooling: A custom Go-based CLI tool wrapped by dev.fish.
  • Capabilities:
    • Builds Go binaries for multiple platforms (Windows, Linux, Android).
    • Compiles Vue.js frontends (npm run build) and embeds them into Go binaries.
    • Handles CA certificate generation and injection.

Data Flow & Communication

  1. Startup & Discovery:

    • When the Client starts, it scans the local subnet (sending TCP probes) or uses fallback IPs to find the Discovery Server.
    • Upon connection, it performs a TCP Handshake (TLS-secured) to register its IP and API port.
    • It maintains a persistent Heartbeat connection.

  2. Sharing a Resource:

    • User inputs a URL in the GUI.
    • The core/proxy module creates a local HTTP listener.
    • Traffic to this listener is proxied to the target URL, potentially with header/body modifications.

  3. Log Streaming:

    • Clients stream internal logs to the Discovery Server via a WebSocket connection (/upload-logs).
    • Admins can view these logs in real-time on the Discovery Dashboard, which also connects via WebSocket.
    • The server maintains a memory buffer (last 1000 lines) for initial state on connection.

  4. Updates:

    • The system supports auto-updates. Clients query the Discovery Server for the latest version and can trigger remote updates.