Goch 🚀

A lightweight, terminal-first LAN chat app written in Go. Goch discovers peers on your local network and lets you chat in real time through a clean TUI powered by Bubble Tea.

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Features ✨

• LAN presence discovery via UDP broadcast (default port 8787)
• Direct user-to-user chat via UDP unicast (default port 8989)
• Modern terminal UI using Bubble Tea and Lipgloss
• Keyboard-first UX: select a user, type, Enter to send; quit with q or Ctrl+C
• Auto-detects subnet broadcast address for discovery
• Simple, readable Go code with internal packages

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Install, build, run 🛠️

Prereqs: Go 1.20+ recommended (works with Go modules), a local LAN.

git clone https://github.com/huseynovvusal/goch.git
cd goch
make build    # builds ./bin/goch
./bin/goch    # run

Run all tests:

make test

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How it works 🧠

• Discovery: each client periodically broadcasts its name on the LAN using UDP broadcast on port 8787. Peers listening on that port add/update the online user list.
• Chat: when you select a user, messages are sent directly to that peer’s IP using UDP unicast on port 8989. Messages are JSON-encoded and include sender info (name, IP) and content.

Key files:

• internal/discovery/: BroadcastPresence, ListenForPresence, in-memory online user tracking
• internal/chat/: SendChatMessage, ListenForChatMessages, NetworkMessage model
• internal/tui/: Bubble Tea model that renders online users, handles selection, and shows a chat pane + input
• internal/utils/network/: auto-detect subnet broadcast address via interface + mask math

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Usage ☕

1. Start goch on at least two machines on the same LAN (Wi‑Fi/Ethernet).
2. Enter your name.
3. Wait a moment for discovery; pick a user with ↑/↓, then press Enter to start chatting.
4. Type a message and press Enter to send.
5. Quit with q or Ctrl+C.

Notes:

• Your own identity (name + IP) is shown under the greeting and is not included in the online list.
• The first discovered user is auto-selected so you see a > cursor by default when the list is non-empty.

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Configuration ⚙️

Defaults live in internal/config/config.go.

• Presence (broadcast) port: 8787
• Chat (unicast) port: 8989
• Online user refresh interval: see ONLINE_USERS_REFRESH_INTERVAL

Network helper:

• The app computes the subnet broadcast address from the active IPv4 interface (network = ip & mask; broadcast = ip | ~mask) and uses it for presence broadcasting.

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Troubleshooting 🧩

If you don’t see other users:

• Ensure both machines are on the same subnet (e.g., 192.168.100.x). Check with ip a (Linux) or ifconfig/ipconfig getifaddr en0 (macOS).
• Firewalls can block UDP broadcast/unicast. Temporarily disable to test: Linux sudo ufw disable, macOS System Settings → Network → Firewall → Off.
• Some routers block global broadcast 255.255.255.255. The app auto-detects the subnet broadcast (e.g., 192.168.100.255).
• AP/Client isolation: disable in your router if clients cannot see each other.
• VPNs/multiple interfaces can route packets incorrectly. Disconnect VPNs and use the same physical network.
• Use packet capture to confirm traffic:
  • On Linux: sudo tcpdump -i any udp port 8787 (presence) or sudo tcpdump -i any udp port 8989 (chat)
  • On macOS: sudo tcpdump -i any udp port 8787 or sudo tcpdump -i any udp port 8989

If macOS sees HP but HP doesn’t see macOS:

• Verify you can ping each other both ways. If one direction fails, resolve network/firewall first.
• Confirm the app sends chat to the peer’s actual LAN IP (not broadcast) and listens on 0.0.0.0:8989.

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Keyboard shortcuts ⌨️

• Enter — submit name / send message (context-sensitive)
• ↑/↓ — navigate users
• q / Ctrl+C — quit

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Contributing 🤝

Contributions are welcome! Please read CONTRIBUTING.md for how to set up your environment, run tests, and submit PRs.

Quick start:

git checkout -b feat/awesome
make test
make build

Open a PR against main with a clear description and screenshots (if UI changes).

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License 📄

This project is licensed under the Apache License 2.0 — see LICENSE.