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84 lines
2.4 KiB
84 lines
2.4 KiB
import socket
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import bz2
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import io
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from a2s.exceptions import BrokenMessageError
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from a2s.byteio import ByteReader
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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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class A2SFragment:
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def __init__(self, message_id, fragment_count, fragment_id, mtu,
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decompressed_size=0, crc=0, payload=b""):
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self.message_id = message_id
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self.fragment_count = fragment_count
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self.fragment_id = fragment_id
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self.mtu = mtu
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self.decompressed_size = decompressed_size
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self.crc = crc
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self.payload = payload
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@property
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def is_compressed(self):
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return bool(self.message_id & (1 << 15))
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def decode_fragment(data):
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reader = ByteReader(
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io.BytesIO(data), endian="<", encoding="utf-8")
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frag = A2SFragment(
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message_id=reader.read_uint32(),
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fragment_count=reader.read_uint8(),
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fragment_id=reader.read_uint8(),
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mtu=reader.read_uint16()
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)
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if frag.is_compressed:
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frag.decompressed_size = reader.read_uint32()
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frag.crc = reader.read_uint32()
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frag.payload = bz2.decompress(reader.read())
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else:
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frag.payload = reader.read()
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return frag
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class A2SStream:
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def __init__(self, address, timeout):
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self.address = address
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self._socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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self._socket.settimeout(timeout)
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def __del__(self):
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self.close()
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def send(self, data):
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packet = HEADER_SIMPLE + data
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self._socket.sendto(packet, self.address)
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def recv(self):
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packet = self._socket.recv(65535)
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header = packet[:4]
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data = packet[4:]
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if header == HEADER_SIMPLE:
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return data
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elif header == HEADER_MULTI:
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fragments = [decode_fragment(data)]
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while len(fragments) < fragments[0].fragment_count:
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packet = self._socket.recv(4096)
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fragments.append(decode_fragment(packet[4:]))
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fragments.sort(key=lambda f: f.fragment_id)
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return b"".join(fragment.payload for fragment in fragments)
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else:
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raise BrokenMessageError(
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"Invalid packet header: " + repr(header))
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def close(self):
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self._socket.close()
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def request(address, data, timeout):
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stream = A2SStream(address, timeout)
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stream.send(data)
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resp = stream.recv()
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stream.close()
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return resp
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