asyncio.server: how to filter on remote IP-address

I have a Tcp socket server class that is to run in CPython and MicroPython. It does, no problem there. Only I would like to extend its functionality with an IP filter. From an earlier version that still was a http server, I have a regular expression pattern to match the requesting IP-address. But where can I step in and inspect the remote address to accept or refuse the connection?

Note: the reader object in newConnection has no attribute '_transport' in microPython.

def log(*args, prio = 0):
    if prio >= 0:
        print(*args)



class TcpServer(SocketBase):
    
    def __init__(self, port=8888, requestHandler = None, ipMask = r"192.168.(\d+).(\d+)|localhost|127.0.0.1"):
        '''
        :param requestHandler: callable with parameters request, response
        '''
        super().__init__(host="0.0.0.0", port = port)
        self.requestHandler = requestHandler
        self.ipRange        = re.compile(ipMask)
        self.timeout        = TimeOut()

    
    async def start(self):
        self.server = await asyncio.start_server(self.newConnection, host=self.host, port=self.port)
        log("server started at ", (self.host, self.port), prio=1)
        
        while True:
            await asyncio.sleep(10)

    
    
    async def newConnection(self, reader, writer):
        log("Connected")

        self.connection = (reader, writer)
        self.timeout.extend(30)
        while not self.timeout.expired():
            if not await self.pollOpenConnection(reader, writer):
                # not data, then doze a while:
                await asyncio.sleep(1./25.)
                
        writer.close()
        log("Disconnected")
        
        

In your connection handler you can find it from the stream writer:

remote_addr = writer.get_extra_info('peername')[0]