arfchat

Local and LAN chat application

Functionality

arfchat uses a multicast protocol to communicate with any and all clients in the same network described in doc/PROTOCOL.md

Right now there is support for:

• nicknames
• joining chatrooms
• sending and receiving messages (yikes)
• relaying messages between networks (debatible)

Project structure

• arfchat: local P2P client source
• arfchatd: internetwork relay daemon source
• libarfchat: protocol de/serialization library
• common: common code
• doc: protocol spec & documentation
• ws_dissect.lua: protocol description file for WireShark inspection

Build

The universal CMake thing

mkdir build && cd build
cmake ..
make

Tested in Linux and OpenBSD.

BSD note: because this application reuses address and port, to launch more than once instance of arfchat (client), all instances have to run as the same user because the BSD kernel has that as a security feature (this is undocumented behaviour). To allow multiple different users to chat on the same BSD system, the sysop must install arfchat system wide, owned by a system user such as \_arfchat and have setuid bit enabled to set its euid to said user. This way the getlogin() functionality is preserved, launched by the different users, and effectively running as the same user. This is confirmed to be also the case in at least FreeBSD and NetBSD, it appears to be a geberal BSD kernel security thing which I didn't know about.