169 lines
5.9 KiB
Python
169 lines
5.9 KiB
Python
"""使用 Windows 凭据管理器保存在线更新密码。
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密码只在调用期间存在于内存，不进入 SQLite、日志或普通错误信息。本模块只使用
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Windows 自带 Credential API，不增加第三方依赖。
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"""
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from __future__ import annotations
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import ctypes
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import sys
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from ctypes import wintypes
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from typing import Optional
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from urllib.parse import urlsplit
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UPDATE_CREDENTIAL_TARGET_PREFIX = "CMAutoBuy/update"
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_CRED_TYPE_GENERIC = 1
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_CRED_PERSIST_LOCAL_MACHINE = 2
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_ERROR_NOT_FOUND = 1168
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class CredentialStoreError(RuntimeError):
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"""Windows 凭据管理器操作失败。"""
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class _CredentialW(ctypes.Structure):
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_fields_ = [
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("Flags", wintypes.DWORD),
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("Type", wintypes.DWORD),
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("TargetName", wintypes.LPWSTR),
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("Comment", wintypes.LPWSTR),
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("LastWritten", wintypes.FILETIME),
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("CredentialBlobSize", wintypes.DWORD),
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("CredentialBlob", ctypes.POINTER(ctypes.c_ubyte)),
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("Persist", wintypes.DWORD),
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("AttributeCount", wintypes.DWORD),
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("Attributes", wintypes.LPVOID),
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("TargetAlias", wintypes.LPWSTR),
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("UserName", wintypes.LPWSTR),
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]
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class WindowsCredentialStore:
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"""读写当前 Windows 用户的通用凭据。"""
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def __init__(self, target: str):
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self._target = target
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if sys.platform != "win32":
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self._api = None
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return
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api = ctypes.WinDLL("Advapi32.dll", use_last_error=True)
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api.CredWriteW.argtypes = [ctypes.POINTER(_CredentialW), wintypes.DWORD]
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api.CredWriteW.restype = wintypes.BOOL
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api.CredReadW.argtypes = [
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wintypes.LPCWSTR,
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wintypes.DWORD,
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wintypes.DWORD,
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ctypes.POINTER(ctypes.POINTER(_CredentialW)),
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]
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api.CredReadW.restype = wintypes.BOOL
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api.CredDeleteW.argtypes = [
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wintypes.LPCWSTR,
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wintypes.DWORD,
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wintypes.DWORD,
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]
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api.CredDeleteW.restype = wintypes.BOOL
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api.CredFree.argtypes = [wintypes.LPVOID]
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api.CredFree.restype = None
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self._api = api
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@property
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def target(self) -> str:
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"""返回不含密码的系统凭据目标名。"""
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return self._target
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@classmethod
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def for_url(cls, url: str) -> "WindowsCredentialStore":
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"""按 URL 源创建独立凭据，避免把一个服务器密码发送给另一个服务器。"""
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parsed = urlsplit(url)
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scheme = parsed.scheme.lower()
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host = (parsed.hostname or "").lower()
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if not scheme or not host:
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raise CredentialStoreError("无法为无效更新地址保存密码")
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port = parsed.port or (443 if scheme == "https" else 80)
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return cls(f"{UPDATE_CREDENTIAL_TARGET_PREFIX}/{scheme}/{host}/{port}")
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def save(self, username: str, password: str) -> None:
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"""保存账号和密码；密码为空时拒绝覆盖已有凭据。"""
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api = self._require_windows()
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normalized_username = username.strip()
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if not normalized_username:
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raise CredentialStoreError("更新账号不能为空")
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if not password:
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raise CredentialStoreError("更新密码不能为空")
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password_bytes = password.encode("utf-16-le")
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if len(password_bytes) > 2560:
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raise CredentialStoreError("更新密码过长")
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blob = ctypes.create_string_buffer(password_bytes)
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credential = _CredentialW()
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credential.Type = _CRED_TYPE_GENERIC
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credential.TargetName = self._target
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credential.CredentialBlobSize = len(password_bytes)
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credential.CredentialBlob = ctypes.cast(
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blob,
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ctypes.POINTER(ctypes.c_ubyte),
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)
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credential.Persist = _CRED_PERSIST_LOCAL_MACHINE
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credential.UserName = normalized_username
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if not api.CredWriteW(ctypes.byref(credential), 0):
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raise self._system_error("保存更新凭据失败")
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def read(self) -> Optional[tuple[str, str]]:
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"""返回保存的 ``(账号, 密码)``；不存在时返回 ``None``。"""
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api = self._require_windows()
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pointer = ctypes.POINTER(_CredentialW)()
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if not api.CredReadW(
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self._target,
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_CRED_TYPE_GENERIC,
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0,
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ctypes.byref(pointer),
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):
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error_code = ctypes.get_last_error()
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if error_code == _ERROR_NOT_FOUND:
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return None
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raise self._system_error("读取更新凭据失败", error_code)
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try:
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credential = pointer.contents
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password_bytes = ctypes.string_at(
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credential.CredentialBlob,
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credential.CredentialBlobSize,
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)
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password = password_bytes.decode("utf-16-le")
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return credential.UserName or "", password
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except (UnicodeDecodeError, ValueError) as exc:
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raise CredentialStoreError("保存的更新凭据无法读取，请重新保存") from exc
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finally:
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api.CredFree(pointer)
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def exists(self) -> bool:
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"""返回是否已经保存更新凭据。"""
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return self.read() is not None
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def delete(self) -> bool:
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"""删除更新凭据；原本不存在时返回 ``False``。"""
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api = self._require_windows()
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if api.CredDeleteW(self._target, _CRED_TYPE_GENERIC, 0):
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return True
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error_code = ctypes.get_last_error()
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if error_code == _ERROR_NOT_FOUND:
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return False
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raise self._system_error("删除更新凭据失败", error_code)
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def _require_windows(self):
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if self._api is None:
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raise CredentialStoreError("更新密码只能保存到 Windows 凭据管理器")
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return self._api
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@staticmethod
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def _system_error(message: str, error_code: Optional[int] = None):
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code = ctypes.get_last_error() if error_code is None else error_code
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return CredentialStoreError(f"{message}（Windows 错误 {code}）")
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