GoTunnel/AGENTS.md

AGENTS.md

This file provides guidance to Codex (Codex.ai/code) when working with code in this repository.

Build Commands

# Build server and client binaries
go build -o server ./cmd/server
go build -o client ./cmd/client

# Run server (zero-config, auto-generates token and TLS cert)
./server
./server -c server.yaml  # with config file

# Run client
./client -s <server>:7000 -t <token>

# Web UI development (in web/ directory)
cd web && npm install && npm run dev    # development server
cd web && npm run build                  # production build (outputs to web/dist/)

# Cross-platform build (Windows PowerShell)
.\scripts\build.ps1

# Cross-platform build (Linux/Mac)
./scripts/build.sh all

Architecture Overview

GoTunnel is an intranet penetration tool (similar to frp) with server-centric configuration - clients require zero configuration and receive mapping rules from the server after authentication.

Core Design

• Yamux Multiplexing: Single TCP connection carries both control (auth, config, heartbeat) and data channels
• Binary Protocol: [Type(1 byte)][Length(4 bytes)][Payload(JSON)] - see pkg/protocol/message.go
• TLS by Default: Auto-generated self-signed ECDSA P-256 certificates, no manual setup required
• Embedded Web UI: Vue.js SPA embedded in server binary via //go:embed
• JS Plugin System: Extensible plugin system using goja JavaScript runtime

Package Structure

cmd/server/          # Server entry point
cmd/client/          # Client entry point
internal/server/
  ├── tunnel/        # Core tunnel server, client session management
  ├── config/        # YAML configuration loading
  ├── db/            # SQLite storage (ClientStore, JSPluginStore interfaces)
  ├── app/           # Web server, SPA handler
  ├── router/        # REST API endpoints (Swagger documented)
  └── plugin/        # Server-side JS plugin manager
internal/client/
  └── tunnel/        # Client tunnel logic, auto-reconnect, plugin execution
pkg/
  ├── protocol/      # Message types and serialization
  ├── crypto/        # TLS certificate generation
  ├── relay/         # Bidirectional data relay (32KB buffers)
  ├── auth/          # JWT authentication
  ├── utils/         # Port availability checking
  ├── version/       # Version info and update checking (GitHub Releases API)
  └── update/        # Shared update logic (download, extract tar.gz/zip)
web/                 # Vue 3 + TypeScript frontend (Vite + naive-ui)
scripts/             # Build scripts (build.sh, build.ps1)

Key Interfaces

• ClientStore (internal/server/db/): Database abstraction for client rules storage
• ServerInterface (internal/server/router/handler/): API handler interface

Proxy Types

1. TCP (default): Direct port forwarding (remote_port → local_ip:local_port)
2. UDP: UDP port forwarding
3. HTTP: HTTP proxy through client network
4. HTTPS: HTTPS proxy through client network
5. SOCKS5: SOCKS5 proxy through client network

Data Flow

External User → Server Port → Yamux Stream → Client → Local Service

Configuration

• Server: YAML config + SQLite database for client rules and JS plugins
• Client: Command-line flags only (server address, token)
• Default ports: 7000 (tunnel), 7500 (web console)

API Documentation

The server provides Swagger-documented REST APIs at /api/.

Key Endpoints

• POST /api/auth/login - JWT authentication
• GET /api/clients - List all clients
• GET /api/client/{id} - Get client details
• PUT /api/client/{id} - Update client config
• POST /api/client/{id}/push - Push config to online client
• POST /api/client/{id}/plugin/{name}/{action} - Plugin actions (start/stop/restart/delete)
• GET /api/plugins - List registered plugins
• GET /api/update/check/server - Check server updates
• POST /api/update/apply/server - Apply server update

Update System

Both server and client support self-update from GitHub releases.

• Release assets are compressed archives (.tar.gz for Linux/Mac, .zip for Windows)
• The pkg/update/ package handles download, extraction, and binary replacement
• Updates can be triggered from the Web UI at /update page