182 lines
6.0 KiB
Python
182 lines
6.0 KiB
Python
import asyncio
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from .utils import encode_uvarint, decode_uvarint_from_stream
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from .mplex_stream import MplexStream
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from ..muxed_connection_interface import IMuxedConn
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class Mplex(IMuxedConn):
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# pylint: disable=too-many-instance-attributes
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"""
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reference: https://github.com/libp2p/go-mplex/blob/master/multiplex.go
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"""
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def __init__(self, conn, initiator):
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"""
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create a new muxed connection
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:param conn: an instance of raw connection
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:param initiator: boolean to prevent multiplex with self
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"""
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self.raw_conn = conn
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self.initiator = initiator
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# Mapping from stream ID -> buffer of messages for that stream
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self.buffers = {}
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self.stream_queue = asyncio.Queue()
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self._next_id = 0 if self.initiator else 1
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self.data_buffer = bytearray()
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# The initiator need not read upon construction time.
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# It should read when the user decides that it wants to read from the constructed stream.
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if not initiator:
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asyncio.ensure_future(self.handle_incoming())
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def _next_stream_id(self):
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"""
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Get next available stream id
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:return: next available stream id for the connection
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"""
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next_id = self._next_id
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self._next_id += 2
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return next_id
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def close(self):
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"""
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close the stream muxer and underlying raw connection
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"""
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self.raw_conn.close()
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def is_closed(self):
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"""
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check connection is fully closed
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:return: true if successful
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"""
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async def read_buffer(self, stream_id):
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"""
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Read a message from stream_id's buffer, check raw connection for new messages
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:param stream_id: stream id of stream to read from
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:return: message read
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"""
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# Empty buffer or nonexistent stream
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# TODO: propagate up timeout exception and catch
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if stream_id not in self.buffers or self.buffers[stream_id].empty():
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await self.handle_incoming()
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if stream_id in self.buffers:
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return await self._read_buffer_exists(stream_id)
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return None
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async def _read_buffer_exists(self, stream_id):
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"""
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Reads from raw connection with the assumption that the message buffer for stream_id exsits
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:param stream_id: stream id of stream to read from
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:return: message read
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"""
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try:
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data = await asyncio.wait_for(self.buffers[stream_id].get(), timeout=5)
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return data
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except asyncio.TimeoutError:
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return None
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async def open_stream(self, protocol_id, peer_id, multi_addr):
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"""
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creates a new muxed_stream
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:param protocol_id: protocol_id of stream
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:param stream_id: stream_id of stream
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:param peer_id: peer_id that stream connects to
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:param multi_addr: multi_addr that stream connects to
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:return: a new stream
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"""
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stream_id = self._next_stream_id()
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stream = MplexStream(stream_id, multi_addr, self)
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self.buffers[stream_id] = asyncio.Queue()
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return stream
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async def accept_stream(self):
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"""
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accepts a muxed stream opened by the other end
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:return: the accepted stream
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"""
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# TODO update to pull out protocol_id from message
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protocol_id = "/echo/1.0.0"
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stream_id = await self.stream_queue.get()
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stream = MplexStream(stream_id, False, self)
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return stream, stream_id, protocol_id
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async def send_message(self, flag, data, stream_id):
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"""
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sends a message over the connection
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:param header: header to use
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:param data: data to send in the message
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:param stream_id: stream the message is in
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:return: True if success
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"""
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# << by 3, then or with flag
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header = (stream_id << 3) | flag
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header = encode_uvarint(header)
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if data is None:
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data_length = encode_uvarint(0)
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_bytes = header + data_length
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else:
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data_length = encode_uvarint(len(data))
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_bytes = header + data_length + data
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return await self.write_to_stream(_bytes)
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async def write_to_stream(self, _bytes):
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"""
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writes a byte array to a raw connection
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:param _bytes: byte array to write
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:return: length written
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"""
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self.raw_conn.writer.write(_bytes)
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await self.raw_conn.writer.drain()
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return len(_bytes)
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async def handle_incoming(self):
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"""
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Read a message off of the raw connection and add it to the corresponding message buffer
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"""
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# TODO Deal with other types of messages using flag (currently _)
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# TODO call read_message in loop to handle case message for other stream was in conn
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stream_id, _, message = await self.read_message()
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if stream_id not in self.buffers:
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self.buffers[stream_id] = asyncio.Queue()
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await self.stream_queue.put(stream_id)
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await self.buffers[stream_id].put(message)
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async def read_chunk(self):
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"""
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Read a chunk of bytes off of the raw connection into data_buffer
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"""
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# unused now but possibly useful in the future
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try:
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chunk = await asyncio.wait_for(self.raw_conn.reader.read(-1), timeout=5)
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self.data_buffer += chunk
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except asyncio.TimeoutError:
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print('timeout!')
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return
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async def read_message(self):
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"""
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Read a single message off of the raw connection
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:return: stream_id, flag, message contents
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"""
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try:
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header = await decode_uvarint_from_stream(self.raw_conn.reader)
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length = await decode_uvarint_from_stream(self.raw_conn.reader)
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message = await asyncio.wait_for(self.raw_conn.reader.read(length), timeout=5)
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except asyncio.TimeoutError:
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print("message malformed")
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return None, None, None
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flag = header & 0x07
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stream_id = header >> 3
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return stream_id, flag, message
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