class Forwarding(Module):
"""
系统报文的接收和发送，
接收时，通过检查报文的类型字段，将收到的报文转发关心该类型报文的模块；
发送时，通过network模块，将报文发送给指定的controller，
若controller为自己或为空则直接转给关心该类型报文的模块。
因此，Forwarding模块可以作为Controller间报文传递的渠道，
也可以作为模块间交互信息的渠道
"""
def __init__(self, controller):
self._myself = controller
self._my_id = controller.get_id()
self._my_address = controller.get_address()
self._transformer = PacketTransformer()
self._dispatcher = PacketDispatcher(self._transformer)
def start(self):
core.network.register_data_handler(self._dispatcher)
def register_handler(self, packet_type, packet_handler):
"""
为某种报文类型注册Handler，当收到该类型的Packet时，会调用相应Handler的handle方法
"""
self._dispatcher.register_handler(packet_type, packet_handler)
def forward(self, packet):
"""
若指定Controller，则向指定的Controller发送Packet。
若不指定Controlller，则自己Controller内部关心该类型报文的模块将接收到该报文
"""
dst = packet.dst
if not dst or dst.get_id() == self._my_id:
return self._dispatch(packet)
address = core.routing.get_address(dst)
if address == self._my_address:
return self._dispatch(packet)
if address:
# logger.debug('Sending Packet to %s (address: %s), %s' % (dst, address, packet))
data = self._transformer.packet_to_data(packet)
return core.network.send(address, data)
else:
logger.warning("Can not find address for %s" % (dst))
def _dispatch(self, packet):
"""
向自己发送报文，为了简化模块的设计，模块与模块之间的通信可以使用该方法，
该方法会直接调用关心该类型报文的Handler，而无需经过内核转发
"""
self._dispatcher._handle(packet)
def __init__(self, controller):
self._myself = controller
self._my_id = controller.get_id()
self._my_address = controller.get_address()
self._transformer = PacketTransformer()
self._dispatcher = PacketDispatcher(self._transformer)