Warzone 2100 Lobby server

lobby_server.py

#! /usr/bin/env python3

import sys, threading, socketserver, struct, copy

motd = sys.argv[1].encode() if len(sys.argv) > 1 else b'Welcome to Warzone 2100 lobby server'

game_size_host = struct.calcsize('!I64si4B')
game_size = game_size_host + struct.calcsize('40s2iI2H2I40s40s157sH40s40s64s255s9I')

lock = threading.Lock()
games = {}
game_id = 0

class RequestHandler(socketserver.BaseRequestHandler):
    def handle(self):
        def log(message): print(f'{self.client_address[0]}: {message}')

        log('connect')
        try:
            def send(binary_format, *data): self.request.sendall(struct.pack(binary_format, *data))
            
            def receive(size, received = None):
                if received is None: received = bytearray()
                while True:
                    size_left = size - len(received)
                    if size_left <= 0: break
                    chunk = self.request.recv(size_left)
                    if len(chunk) == 0: raise EOFError()
                    received += chunk
                return received
            
            def unpack_game(game_id, data):
                host = self.client_address[0].encode() + b'\0'
                #host = b'127.0.0.1\0'
                data[game_size_host : game_size_host + len(host)] = host
                with lock: games[game_id] = data

            def remove_game(game_id):
                with lock: del games[game_id]

            def send_games():
                with lock: games_snapshot = copy.deepcopy(games)
                send('!I', len(games_snapshot))
                for game in games_snapshot.values(): send(f'!{game_size}s', game)
            
            def send_status_and_motd(): send(f'!2I{len(motd)}s', 200, len(motd), motd)

            def send_more_games(): send('!I', 0)
            
            def send_game_id():
                with lock:
                    global game_id
                    game_id += 1
                    current_game_id = game_id
                send('!I', current_game_id)
                return current_game_id

            data = receive(5)
            if data == b'list\0':
                log('list')
                send_games()
                send_status_and_motd()
                send_more_games()
            elif data == b'gaId\0':
                log('host start')
                game_id = send_game_id()
                data = receive(5)
                if data == b'addg\0':
                    data = receive(game_size)
                    unpack_game(game_id, data)
                    try:
                        send_status_and_motd()
                        while True:
                            data = receive(5)
                            if data == b'keep\0': log('host keep')
                            else:
                                log('host update')
                                receive(game_size, data)
                                unpack_game(game_id, data)
                                send_status_and_motd()
                    finally: remove_game(game_id)
        except EOFError: pass
        finally: log('disconnect')

class ThreadedTCPServer(socketserver.ThreadingMixIn, socketserver.TCPServer): pass
with ThreadedTCPServer(('0.0.0.0', 9990), RequestHandler) as ss: ss.serve_forever()

To use it, one has to edit his local WZ config file, and change the entry masterserver_name=
e.g. masterserver_name=lobby.warzone2100.retropaganda.info