upnp.py 文件源码

def search_device(self):
        """
        Triggers a UPnP device discovery.

        The returned deferred will be called with the L{UPnPDevice} that has
        been found in the LAN.

        @return: A deferred called with the detected L{UPnPDevice} instance.
        @rtype: L{twisted.internet.defer.Deferred}
        """
        if self._discovery is not None:
            raise ValueError('already used')
        self._discovery = defer.Deferred()
        self._discovery_timeout = reactor.callLater(6, self._on_discovery_timeout)

        attempt = 0
        mcast = None
        while True:
            try:
                self.mcast = reactor.listenMulticast(1900+attempt, self)
                break
            except CannotListenError:
                attempt = random.randint(0, 500)

        # joined multicast group, starting upnp search
        self.mcast.joinGroup('239.255.255.250', socket.INADDR_ANY)

        self.transport.write(_UPNP_SEARCH_REQUEST, (_UPNP_MCAST, _UPNP_PORT))
        self.transport.write(_UPNP_SEARCH_REQUEST, (_UPNP_MCAST, _UPNP_PORT))
        self.transport.write(_UPNP_SEARCH_REQUEST, (_UPNP_MCAST, _UPNP_PORT))

        return self._discovery

    #Private methods