244 lines
No EOL
6.8 KiB
Python
244 lines
No EOL
6.8 KiB
Python
"""
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Websockets protocol
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"""
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import logging
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import ure as re
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import ustruct as struct
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import urandom as random
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import usocket as socket
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from ucollections import namedtuple
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LOGGER = logging.getLogger(__name__)
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# Opcodes
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OP_CONT = const(0x0)
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OP_TEXT = const(0x1)
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OP_BYTES = const(0x2)
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OP_CLOSE = const(0x8)
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OP_PING = const(0x9)
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OP_PONG = const(0xa)
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# Close codes
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CLOSE_OK = const(1000)
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CLOSE_GOING_AWAY = const(1001)
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CLOSE_PROTOCOL_ERROR = const(1002)
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CLOSE_DATA_NOT_SUPPORTED = const(1003)
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CLOSE_BAD_DATA = const(1007)
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CLOSE_POLICY_VIOLATION = const(1008)
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CLOSE_TOO_BIG = const(1009)
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CLOSE_MISSING_EXTN = const(1010)
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CLOSE_BAD_CONDITION = const(1011)
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URL_RE = re.compile(r'(wss|ws)://([A-Za-z0-9-\.]+)(?:\:([0-9]+))?(/.+)?')
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URI = namedtuple('URI', ('protocol', 'hostname', 'port', 'path'))
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class NoDataException(Exception):
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pass
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class ConnectionClosed(Exception):
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pass
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def urlparse(uri):
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"""Parse ws:// URLs"""
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match = URL_RE.match(uri)
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if match:
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protocol = match.group(1)
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host = match.group(2)
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port = match.group(3)
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path = match.group(4)
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if protocol == 'wss':
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if port is None:
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port = 443
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elif protocol == 'ws':
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if port is None:
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port = 80
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else:
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raise ValueError('Scheme {} is invalid'.format(protocol))
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return URI(protocol, host, int(port), path)
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class Websocket:
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"""
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Basis of the Websocket protocol.
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This can probably be replaced with the C-based websocket module, but
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this one currently supports more options.
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"""
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is_client = False
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def __init__(self, sock):
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self.sock = sock
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self.open = True
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc, tb):
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self.close()
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def settimeout(self, timeout):
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self.sock.settimeout(timeout)
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def read_frame(self, max_size=None):
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"""
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Read a frame from the socket.
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See https://tools.ietf.org/html/rfc6455#section-5.2 for the details.
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"""
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# Frame header
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two_bytes = self.sock.read(2)
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if not two_bytes:
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raise NoDataException
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byte1, byte2 = struct.unpack('!BB', two_bytes)
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# Byte 1: FIN(1) _(1) _(1) _(1) OPCODE(4)
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fin = bool(byte1 & 0x80)
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opcode = byte1 & 0x0f
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# Byte 2: MASK(1) LENGTH(7)
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mask = bool(byte2 & (1 << 7))
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length = byte2 & 0x7f
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if length == 126: # Magic number, length header is 2 bytes
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length, = struct.unpack('!H', self.sock.read(2))
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elif length == 127: # Magic number, length header is 8 bytes
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length, = struct.unpack('!Q', self.sock.read(8))
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if mask: # Mask is 4 bytes
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mask_bits = self.sock.read(4)
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try:
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data = self.sock.read(length)
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except MemoryError:
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# We can't receive this many bytes, close the socket
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if __debug__: LOGGER.debug("Frame of length %s too big. Closing",
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length)
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self.close(code=CLOSE_TOO_BIG)
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return True, OP_CLOSE, None
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if mask:
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data = bytes(b ^ mask_bits[i % 4]
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for i, b in enumerate(data))
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return fin, opcode, data
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def write_frame(self, opcode, data=b''):
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"""
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Write a frame to the socket.
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See https://tools.ietf.org/html/rfc6455#section-5.2 for the details.
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"""
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fin = True
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mask = self.is_client # messages sent by client are masked
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length = len(data)
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# Frame header
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# Byte 1: FIN(1) _(1) _(1) _(1) OPCODE(4)
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byte1 = 0x80 if fin else 0
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byte1 |= opcode
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# Byte 2: MASK(1) LENGTH(7)
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byte2 = 0x80 if mask else 0
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if length < 126: # 126 is magic value to use 2-byte length header
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byte2 |= length
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self.sock.write(struct.pack('!BB', byte1, byte2))
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elif length < (1 << 16): # Length fits in 2-bytes
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byte2 |= 126 # Magic code
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self.sock.write(struct.pack('!BBH', byte1, byte2, length))
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elif length < (1 << 64):
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byte2 |= 127 # Magic code
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self.sock.write(struct.pack('!BBQ', byte1, byte2, length))
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else:
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raise ValueError()
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if mask: # Mask is 4 bytes
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mask_bits = struct.pack('!I', random.getrandbits(32))
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self.sock.write(mask_bits)
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data = bytes(b ^ mask_bits[i % 4]
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for i, b in enumerate(data))
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self.sock.write(data)
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def recv(self):
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"""
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Receive data from the websocket.
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This is slightly different from 'websockets' in that it doesn't
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fire off a routine to process frames and put the data in a queue.
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If you don't call recv() sufficiently often you won't process control
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frames.
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"""
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assert self.open
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while self.open:
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try:
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fin, opcode, data = self.read_frame()
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except NoDataException:
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return ''
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except ValueError:
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LOGGER.debug("Failed to read frame. Socket dead.")
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self._close()
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raise ConnectionClosed()
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if not fin:
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raise NotImplementedError()
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if opcode == OP_TEXT:
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return data.decode('utf-8')
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elif opcode == OP_BYTES:
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return data
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elif opcode == OP_CLOSE:
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self._close()
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return
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elif opcode == OP_PONG:
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# Ignore this frame, keep waiting for a data frame
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continue
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elif opcode == OP_PING:
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# We need to send a pong frame
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if __debug__: LOGGER.debug("Sending PONG")
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self.write_frame(OP_PONG, data)
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# And then wait to receive
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continue
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elif opcode == OP_CONT:
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# This is a continuation of a previous frame
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raise NotImplementedError(opcode)
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else:
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raise ValueError(opcode)
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def send(self, buf):
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"""Send data to the websocket."""
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assert self.open
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if isinstance(buf, str):
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opcode = OP_TEXT
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buf = buf.encode('utf-8')
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elif isinstance(buf, bytes):
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opcode = OP_BYTES
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else:
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raise TypeError()
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self.write_frame(opcode, buf)
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def close(self, code=CLOSE_OK, reason=''):
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"""Close the websocket."""
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if not self.open:
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return
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buf = struct.pack('!H', code) + reason.encode('utf-8')
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self.write_frame(OP_CLOSE, buf)
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self._close()
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def _close(self):
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if __debug__: LOGGER.debug("Connection closed")
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self.open = False
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self.sock.close() |