58 lines
1.3 KiB
Python
58 lines
1.3 KiB
Python
from __future__ import annotations
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import base64
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import hashlib
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import secrets
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import sys
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from .typing import BytesLike
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__all__ = ["accept_key", "apply_mask"]
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GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
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def generate_key() -> str:
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"""
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Generate a random key for the Sec-WebSocket-Key header.
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"""
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key = secrets.token_bytes(16)
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return base64.b64encode(key).decode()
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def accept_key(key: str) -> str:
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"""
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Compute the value of the Sec-WebSocket-Accept header.
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Args:
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key: Value of the Sec-WebSocket-Key header.
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"""
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sha1 = hashlib.sha1((key + GUID).encode()).digest()
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return base64.b64encode(sha1).decode()
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def apply_mask(data: BytesLike, mask: bytes | bytearray) -> bytes:
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"""
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Apply masking to the data of a WebSocket message.
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Args:
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data: Data to mask.
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mask: 4-bytes mask.
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"""
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if len(mask) != 4:
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raise ValueError("mask must contain 4 bytes")
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# Python 3.15+ requires C-contiguous buffers for int.from_bytes().
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if isinstance(data, memoryview) and not data.c_contiguous:
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data = bytes(data)
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data_int = int.from_bytes(data, sys.byteorder)
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mask_repeated = mask * (len(data) // 4) + mask[: len(data) % 4]
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mask_int = int.from_bytes(mask_repeated, sys.byteorder)
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return (data_int ^ mask_int).to_bytes(len(data), sys.byteorder)
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