107 lines
3.8 KiB
Python
107 lines
3.8 KiB
Python
"""Private artifact download ports; object paths never enter public JSON."""
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from __future__ import annotations
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import hashlib
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import os
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import stat
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from dataclasses import dataclass
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from pathlib import Path, PurePosixPath
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from typing import Protocol
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from arr_web.contracts import PortalError
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MAX_DOWNLOAD_BYTES = 100 * 1024 * 1024
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ALLOWED_DOWNLOAD_KINDS = frozenset(
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{"daily_xlsx", "monthly_xlsx", "company_ten_day_xlsx"}
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)
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@dataclass(frozen=True)
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class ArtifactDescriptor:
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file_kind: str
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original_filename: str
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storage_key: str
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sha256: str
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byte_size: int
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mime_type: str
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def validate(self) -> None:
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path = PurePosixPath(self.storage_key)
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if (
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self.file_kind not in ALLOWED_DOWNLOAD_KINDS
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or not self.original_filename
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or PurePosixPath(self.original_filename).name != self.original_filename
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or "/" in self.original_filename
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or "\\" in self.original_filename
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or "\x00" in self.original_filename
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or not self.storage_key
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or path.is_absolute()
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or "." in path.parts
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or ".." in path.parts
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or "\\" in self.storage_key
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or len(self.sha256) != 64
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or any(character not in "0123456789abcdef" for character in self.sha256)
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or not 0 < self.byte_size <= MAX_DOWNLOAD_BYTES
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or not self.mime_type
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):
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raise PortalError("DOWNLOAD_REFERENCE_INVALID", "文件身份无效", 500)
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class ArtifactReader(Protocol):
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def read(self, descriptor: ArtifactDescriptor) -> bytes:
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...
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class UnavailableArtifactReader:
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def read(self, descriptor: ArtifactDescriptor) -> bytes:
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raise PortalError("DOWNLOAD_UNAVAILABLE", "文件读取服务暂不可用", 503)
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class ControlledProjectArtifactReader:
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"""Development/local publication reader constrained to one project root."""
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def __init__(self, project_root: Path) -> None:
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self._project_root = project_root.resolve()
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def read(self, descriptor: ArtifactDescriptor) -> bytes:
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descriptor.validate()
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path = (self._project_root / descriptor.storage_key).resolve()
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try:
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path.relative_to(self._project_root)
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metadata = path.lstat()
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except (ValueError, OSError):
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raise PortalError("DOWNLOAD_UNAVAILABLE", "文件读取服务暂不可用", 503) from None
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if path.is_symlink() or not stat.S_ISREG(metadata.st_mode):
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raise PortalError("DOWNLOAD_REFERENCE_INVALID", "文件身份无效", 500)
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if metadata.st_size != descriptor.byte_size:
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raise PortalError("DOWNLOAD_IDENTITY_MISMATCH", "文件完整性校验失败", 503)
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digest = hashlib.sha256()
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chunks: list[bytes] = []
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descriptor_fd = -1
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total = 0
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try:
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descriptor_fd = os.open(path, os.O_RDONLY | getattr(os, "O_NOFOLLOW", 0))
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with os.fdopen(descriptor_fd, "rb") as source:
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descriptor_fd = -1
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while True:
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chunk = source.read(1024 * 1024)
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if not chunk:
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break
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total += len(chunk)
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if total > MAX_DOWNLOAD_BYTES:
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raise PortalError("DOWNLOAD_TOO_LARGE", "文件超过下载限制", 413)
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digest.update(chunk)
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chunks.append(chunk)
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except PortalError:
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raise
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except OSError:
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raise PortalError("DOWNLOAD_UNAVAILABLE", "文件读取服务暂不可用", 503) from None
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finally:
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if descriptor_fd >= 0:
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os.close(descriptor_fd)
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if total != descriptor.byte_size or digest.hexdigest() != descriptor.sha256:
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raise PortalError("DOWNLOAD_IDENTITY_MISMATCH", "文件完整性校验失败", 503)
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return b"".join(chunks)
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