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