server.py

# server_async.py
import asyncio

class ServerConnection:
    def __init__(self, msg):
        self.msg = msg
        self.connections = {}  # writer -> addr

    async def handle_peer(self, reader, writer):
        addr = writer.get_extra_info("peername")
        self.connections[writer] = addr
        print(f"{addr} connected")
        await self.send_peers()

        try:
            while True:
                data = await reader.read(1024)
                if not data:
                    break

                text = data.decode("utf-8")

                if text.lower().startswith("q"):
                    break

                elif text == "req":
                    writer.write(self.msg)
                    await writer.drain()

        finally:
            await self.disconnect(writer)

    async def disconnect(self, writer):
        addr = self.connections.pop(writer, None)
        if addr:
            print(f"{addr} disconnected")
        writer.close()
        await writer.wait_closed()
        await self.send_peers()

    async def send_peers(self):
        peer_list = ",".join(addr[0] for addr in self.connections.values()) + ","
        payload = b"\x11" + peer_list.encode("utf-8")

        for writer in list(self.connections.keys()):
            writer.write(payload)
            await writer.drain()

    async def run(self):
        server = await asyncio.start_server(
            self.handle_peer, "127.0.0.1", 3000
        )
        print("------------ Server Running ---------------------")
        async with server:
            await server.serve_forever()