mirror of
https://github.com/varun-r-mallya/py-libp2p.git
synced 2025-12-31 20:36:24 +00:00
106 lines
2.9 KiB
Python
106 lines
2.9 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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from abc import (
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abstractmethod,
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)
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from typing import (
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Literal,
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)
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from libp2p.io.abc import (
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MsgReadWriteCloser,
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Reader,
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ReadWriteCloser,
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)
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from libp2p.io.utils import (
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read_exactly,
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)
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from libp2p.utils import (
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decode_uvarint_from_stream,
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encode_varint_prefixed,
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)
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from .exceptions import (
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MessageTooLarge,
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)
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BYTE_ORDER: Literal["big", "little"] = "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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try:
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len_prefix = len(msg_bytes).to_bytes(size_len_bytes, byteorder=BYTE_ORDER)
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except OverflowError:
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raise ValueError(
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"msg_bytes is too large for `size_len_bytes` bytes length: "
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f"msg_bytes={msg_bytes!r}, size_len_bytes={size_len_bytes}"
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)
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return len_prefix + msg_bytes
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class BaseMsgReadWriter(MsgReadWriteCloser):
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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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async def read_msg(self) -> bytes:
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length = await self.next_msg_len()
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return await read_exactly(self.read_write_closer, length)
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@abstractmethod
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async def next_msg_len(self) -> int:
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...
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@abstractmethod
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def encode_msg(self, msg: bytes) -> bytes:
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...
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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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encoded_msg = self.encode_msg(msg)
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await self.read_write_closer.write(encoded_msg)
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class FixedSizeLenMsgReadWriter(BaseMsgReadWriter):
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size_len_bytes: int
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async def next_msg_len(self) -> int:
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return await read_length(self.read_write_closer, self.size_len_bytes)
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def encode_msg(self, msg: bytes) -> bytes:
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return encode_msg_with_length(msg, self.size_len_bytes)
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class VarIntLengthMsgReadWriter(BaseMsgReadWriter):
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max_msg_size: int
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async def next_msg_len(self) -> int:
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msg_len = await decode_uvarint_from_stream(self.read_write_closer)
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if msg_len > self.max_msg_size:
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raise MessageTooLarge(
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f"msg_len={msg_len} > max_msg_size={self.max_msg_size}"
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)
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return msg_len
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def encode_msg(self, msg: bytes) -> bytes:
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msg_len = len(msg)
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if msg_len > self.max_msg_size:
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raise MessageTooLarge(
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f"msg_len={msg_len} > max_msg_size={self.max_msg_size}"
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)
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return encode_varint_prefixed(msg)
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