191 lines
6.9 KiB
Python
191 lines
6.9 KiB
Python
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import functools
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from engineio import json as _json
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(CONNECT, DISCONNECT, EVENT, ACK, CONNECT_ERROR, BINARY_EVENT, BINARY_ACK) = \
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(0, 1, 2, 3, 4, 5, 6)
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packet_names = ['CONNECT', 'DISCONNECT', 'EVENT', 'ACK', 'CONNECT_ERROR',
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'BINARY_EVENT', 'BINARY_ACK']
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class Packet(object):
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"""Socket.IO packet."""
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# the format of the Socket.IO packet is as follows:
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#
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# packet type: 1 byte, values 0-6
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# num_attachments: ASCII encoded, only if num_attachments != 0
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# '-': only if num_attachments != 0
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# namespace, followed by a ',': only if namespace != '/'
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# id: ASCII encoded, only if id is not None
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# data: JSON dump of data payload
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uses_binary_events = True
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json = _json
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def __init__(self, packet_type=EVENT, data=None, namespace=None, id=None,
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binary=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.namespace = namespace
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self.id = id
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if self.uses_binary_events and \
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(binary or (binary is None and self._data_is_binary(
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self.data))):
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if self.packet_type == EVENT:
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self.packet_type = BINARY_EVENT
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elif self.packet_type == ACK:
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self.packet_type = BINARY_ACK
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else:
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raise ValueError('Packet does not support binary payload.')
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self.attachment_count = 0
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self.attachments = []
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if encoded_packet:
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self.attachment_count = self.decode(encoded_packet) or 0
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def encode(self):
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"""Encode the packet for transmission.
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If the packet contains binary elements, this function returns a list
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of packets where the first is the original packet with placeholders for
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the binary components and the remaining ones the binary attachments.
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"""
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encoded_packet = str(self.packet_type)
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if self.packet_type == BINARY_EVENT or self.packet_type == BINARY_ACK:
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data, attachments = self._deconstruct_binary(self.data)
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encoded_packet += str(len(attachments)) + '-'
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else:
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data = self.data
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attachments = None
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if self.namespace is not None and self.namespace != '/':
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encoded_packet += self.namespace + ','
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if self.id is not None:
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encoded_packet += str(self.id)
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if data is not None:
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encoded_packet += self.json.dumps(data, separators=(',', ':'))
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if attachments is not None:
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encoded_packet = [encoded_packet] + attachments
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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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The return value indicates how many binary attachment packets are
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necessary to fully decode the packet.
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"""
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ep = encoded_packet
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try:
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self.packet_type = int(ep[0:1])
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except TypeError:
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self.packet_type = ep
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ep = ''
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self.namespace = None
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self.data = None
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ep = ep[1:]
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dash = ep.find('-')
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attachment_count = 0
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if dash > 0 and ep[0:dash].isdigit():
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if dash > 10:
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raise ValueError('too many attachments')
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attachment_count = int(ep[0:dash])
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ep = ep[dash + 1:]
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if ep and ep[0:1] == '/':
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sep = ep.find(',')
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if sep == -1:
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self.namespace = ep
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ep = ''
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else:
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self.namespace = ep[0:sep]
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ep = ep[sep + 1:]
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q = self.namespace.find('?')
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if q != -1:
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self.namespace = self.namespace[0:q]
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if ep and ep[0].isdigit():
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i = 1
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end = len(ep)
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while i < end:
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if not ep[i].isdigit() or i >= 100:
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break
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i += 1
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self.id = int(ep[:i])
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ep = ep[i:]
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if len(ep) > 0 and ep[0].isdigit():
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raise ValueError('id field is too long')
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if ep:
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self.data = self.json.loads(ep)
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return attachment_count
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def add_attachment(self, attachment):
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if self.attachment_count <= len(self.attachments):
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raise ValueError('Unexpected binary attachment')
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self.attachments.append(attachment)
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if self.attachment_count == len(self.attachments):
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self.reconstruct_binary(self.attachments)
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return True
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return False
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def reconstruct_binary(self, attachments):
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"""Reconstruct a decoded packet using the given list of binary
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attachments.
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"""
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self.data = self._reconstruct_binary_internal(self.data,
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self.attachments)
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def _reconstruct_binary_internal(self, data, attachments):
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if isinstance(data, list):
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return [self._reconstruct_binary_internal(item, attachments)
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for item in data]
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elif isinstance(data, dict):
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if data.get('_placeholder') and 'num' in data:
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return attachments[data['num']]
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else:
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return {key: self._reconstruct_binary_internal(value,
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attachments)
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for key, value in data.items()}
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else:
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return data
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def _deconstruct_binary(self, data):
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"""Extract binary components in the packet."""
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attachments = []
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data = self._deconstruct_binary_internal(data, attachments)
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return data, attachments
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def _deconstruct_binary_internal(self, data, attachments):
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if isinstance(data, bytes):
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attachments.append(data)
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return {'_placeholder': True, 'num': len(attachments) - 1}
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elif isinstance(data, list):
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return [self._deconstruct_binary_internal(item, attachments)
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for item in data]
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elif isinstance(data, dict):
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return {key: self._deconstruct_binary_internal(value, attachments)
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for key, value in data.items()}
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else:
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return data
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def _data_is_binary(self, data):
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"""Check if the data contains binary components."""
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if isinstance(data, bytes):
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return True
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elif isinstance(data, list):
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return functools.reduce(
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lambda a, b: a or b, [self._data_is_binary(item)
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for item in data], False)
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elif isinstance(data, dict):
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return functools.reduce(
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lambda a, b: a or b, [self._data_is_binary(item)
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for item in data.values()],
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False)
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else:
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return False
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def _to_dict(self):
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d = {
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'type': self.packet_type,
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'data': self.data,
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'nsp': self.namespace,
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}
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if self.id:
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d['id'] = self.id
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return d
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