65 lines
2.1 KiB
Python
65 lines
2.1 KiB
Python
"""
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``msgio`` is an implementation of `https://github.com/libp2p/go-msgio`.
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from that repo: "a simple package to r/w length-delimited slices."
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NOTE: currently missing the capability to indicate lengths by "varint" method.
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"""
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# TODO unify w/ https://github.com/libp2p/py-libp2p/blob/1aed52856f56a4b791696bbcbac31b5f9c2e88c9/libp2p/utils.py#L85-L99 # noqa: E501
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from typing import Optional
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from libp2p.io.abc import MsgReadWriter, Reader, ReadWriteCloser
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from libp2p.io.utils import read_exactly
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SIZE_NOISE_LEN_BYTES = 2
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SIZE_SECIO_LEN_BYTES = 4
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BYTE_ORDER = "big"
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async def read_length(reader: Reader, size_len_bytes: int) -> int:
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length_bytes = await read_exactly(reader, size_len_bytes)
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return int.from_bytes(length_bytes, byteorder=BYTE_ORDER)
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def encode_msg_with_length(msg_bytes: bytes, size_len_bytes: int) -> bytes:
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len_prefix = len(msg_bytes).to_bytes(size_len_bytes, byteorder=BYTE_ORDER)
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return len_prefix + msg_bytes
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class BaseMsgReadWriter(MsgReadWriter):
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next_length: Optional[int]
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read_write_closer: ReadWriteCloser
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size_len_bytes: int
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def __init__(self, read_write_closer: ReadWriteCloser) -> None:
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self.read_write_closer = read_write_closer
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self.next_length = None
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async def read_msg(self) -> bytes:
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length = await self.next_msg_len()
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data = await read_exactly(self.read_write_closer, length)
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if len(data) < length:
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self.next_length = length - len(data)
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else:
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self.next_length = None
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return data
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async def next_msg_len(self) -> int:
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if self.next_length is None:
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self.next_length = await read_length(
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self.read_write_closer, self.size_len_bytes
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)
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return self.next_length
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async def close(self) -> None:
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await self.read_write_closer.close()
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async def write_msg(self, msg: bytes) -> None:
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data = encode_msg_with_length(msg, self.size_len_bytes)
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await self.read_write_closer.write(data)
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class MsgIOReadWriter(BaseMsgReadWriter):
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size_len_bytes = SIZE_SECIO_LEN_BYTES
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