83 lines
3.1 KiB
Python
83 lines
3.1 KiB
Python
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import base64
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from engineio import json as _json
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(OPEN, CLOSE, PING, PONG, MESSAGE, UPGRADE, NOOP) = (0, 1, 2, 3, 4, 5, 6)
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packet_names = ['OPEN', 'CLOSE', 'PING', 'PONG', 'MESSAGE', 'UPGRADE', 'NOOP']
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binary_types = (bytes, bytearray)
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class Packet(object):
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"""Engine.IO packet."""
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json = _json
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def __init__(self, packet_type=NOOP, data=None, encoded_packet=None):
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self.packet_type = packet_type
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self.data = data
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self.encode_cache = None
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if isinstance(data, str):
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self.binary = False
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elif isinstance(data, binary_types):
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self.binary = True
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else:
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self.binary = False
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if self.binary and self.packet_type != MESSAGE:
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raise ValueError('Binary packets can only be of type MESSAGE')
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if encoded_packet is not None:
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self.decode(encoded_packet)
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def encode(self, b64=False):
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"""Encode the packet for transmission.
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Note: as a performance optimization, subsequent calls to this method
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will return a cached encoded packet, even if the data has changed.
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"""
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if self.encode_cache:
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return self.encode_cache
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if self.binary:
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if b64:
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encoded_packet = 'b' + base64.b64encode(self.data).decode(
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'utf-8')
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else:
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encoded_packet = self.data
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else:
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encoded_packet = str(self.packet_type)
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if isinstance(self.data, str):
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encoded_packet += self.data
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elif isinstance(self.data, dict) or isinstance(self.data, list):
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encoded_packet += self.json.dumps(self.data,
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separators=(',', ':'))
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elif self.data is not None:
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encoded_packet += str(self.data)
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self.encode_cache = encoded_packet
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return encoded_packet
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def decode(self, encoded_packet):
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"""Decode a transmitted package."""
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self.binary = isinstance(encoded_packet, binary_types)
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if not self.binary and len(encoded_packet) == 0:
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raise ValueError('Invalid empty packet received')
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b64 = not self.binary and encoded_packet[0] == 'b'
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if b64:
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self.binary = True
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self.packet_type = MESSAGE
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self.data = base64.b64decode(encoded_packet[1:])
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else:
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if self.binary and not isinstance(encoded_packet, bytes):
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encoded_packet = bytes(encoded_packet)
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if self.binary:
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self.packet_type = MESSAGE
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self.data = encoded_packet
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else:
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self.packet_type = int(encoded_packet[0])
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try:
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self.data = self.json.loads(encoded_packet[1:])
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if isinstance(self.data, int):
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# do not allow integer payloads, see
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# github.com/miguelgrinberg/python-engineio/issues/75
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# for background on this decision
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raise ValueError
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except ValueError:
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self.data = encoded_packet[1:]
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