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69 lines
2.2 KiB
69 lines
2.2 KiB
import asyncio
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import logging
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from a2s.exceptions import BrokenMessageError
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from a2s.a2sfragment import decode_fragment
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HEADER_SIMPLE = b"\xFF\xFF\xFF\xFF"
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HEADER_MULTI = b"\xFE\xFF\xFF\xFF"
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logger = logging.getLogger("a2s")
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class A2SProtocol:
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def __init__(self):
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self.recv_queue = asyncio.Queue()
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self.error_event = asyncio.Event()
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self.error = None
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self.fragment_buf = []
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def connection_made(self, transport):
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self.transport = transport
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def datagram_received(self, packet, addr):
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header = packet[:4]
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payload = packet[4:]
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if header == HEADER_SIMPLE:
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logger.debug("Received single packet: %r", payload)
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self.recv_queue.put_nowait(payload)
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elif header == HEADER_MULTI:
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self.fragment_buf.append(decode_fragment(payload))
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if len(self.fragment_buf) < self.fragment_buf[0].fragment_count:
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return # Wait for more packets to arrive
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self.fragment_buf.sort(key=lambda f: f.fragment_id)
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reassembled = b"".join(
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fragment.payload for fragment in self.fragment_buf)
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logger.debug("Received %s part packet with content: %r",
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len(fragments), reassembled)
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self.recv_queue.put_nowait(reassembled)
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self.fragment_buf = []
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else:
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self.error = BrokenMessageError(
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"Invalid packet header: " + repr(header))
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self.error_event.set()
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def error_received(self, exc):
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self.error = exc
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self.error_event.set()
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def send(self, payload):
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packet = HEADER_SIMPLE + payload
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self.transport.sendto(packet)
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async def recv(self, timeout):
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queue_task = asyncio.create_task(self.recv_queue.get())
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error_task = asyncio.create_task(self.error_event.wait())
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done, pending = await asyncio.wait({queue_task, error_task},
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timeout=timeout, return_when=FIRST_COMPLETED)
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for task in pending: task.cancel()
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if error_task in done:
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error = self.error
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self.error = None
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self.error_event.clear()
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raise error
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if not done:
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raise asyncio.TimeoutError()
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return queue_task.result()
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