import importlib.util import os import stat import typing from email.utils import parsedate import anyio from starlette.datastructures import URL, Headers from starlette.exceptions import HTTPException from starlette.responses import FileResponse, RedirectResponse, Response from starlette.types import Receive, Scope, Send PathLike = typing.Union[str, "os.PathLike[str]"] class NotModifiedResponse(Response): NOT_MODIFIED_HEADERS = ( "cache-control", "content-location", "date", "etag", "expires", "vary", ) def __init__(self, headers: Headers): super().__init__( status_code=304, headers={ name: value for name, value in headers.items() if name in self.NOT_MODIFIED_HEADERS }, ) class StaticFiles: def __init__( self, *, directory: typing.Optional[PathLike] = None, packages: typing.Optional[ typing.List[typing.Union[str, typing.Tuple[str, str]]] ] = None, html: bool = False, check_dir: bool = True, ) -> None: self.directory = directory self.packages = packages self.all_directories = self.get_directories(directory, packages) self.html = html self.config_checked = False if check_dir and directory is not None and not os.path.isdir(directory): raise RuntimeError(f"Directory '{directory}' does not exist") def get_directories( self, directory: typing.Optional[PathLike] = None, packages: typing.Optional[ typing.List[typing.Union[str, typing.Tuple[str, str]]] ] = None, ) -> typing.List[PathLike]: """ Given `directory` and `packages` arguments, return a list of all the directories that should be used for serving static files from. """ directories = [] if directory is not None: directories.append(directory) for package in packages or []: if isinstance(package, tuple): package, statics_dir = package else: statics_dir = "statics" spec = importlib.util.find_spec(package) assert spec is not None, f"Package {package!r} could not be found." assert spec.origin is not None, f"Package {package!r} could not be found." package_directory = os.path.normpath( os.path.join(spec.origin, "..", statics_dir) ) assert os.path.isdir( package_directory ), f"Directory '{statics_dir!r}' in package {package!r} could not be found." directories.append(package_directory) return directories async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None: """ The ASGI entry point. """ assert scope["type"] == "http" if not self.config_checked: await self.check_config() self.config_checked = True path = self.get_path(scope) response = await self.get_response(path, scope) await response(scope, receive, send) def get_path(self, scope: Scope) -> str: """ Given the ASGI scope, return the `path` string to serve up, with OS specific path separators, and any '..', '.' components removed. """ return os.path.normpath(os.path.join(*scope["path"].split("/"))) async def get_response(self, path: str, scope: Scope) -> Response: """ Returns an HTTP response, given the incoming path, method and request headers. """ if scope["method"] not in ("GET", "HEAD"): raise HTTPException(status_code=405) try: full_path, stat_result = await anyio.to_thread.run_sync( self.lookup_path, path ) except PermissionError: raise HTTPException(status_code=401) except OSError: raise if stat_result and stat.S_ISREG(stat_result.st_mode): # We have a static file to serve. return self.file_response(full_path, stat_result, scope) elif stat_result and stat.S_ISDIR(stat_result.st_mode) and self.html: # We're in HTML mode, and have got a directory URL. # Check if we have 'index.html' file to serve. index_path = os.path.join(path, "index.html") full_path, stat_result = await anyio.to_thread.run_sync( self.lookup_path, index_path ) if stat_result is not None and stat.S_ISREG(stat_result.st_mode): if not scope["path"].endswith("/"): # Directory URLs should redirect to always end in "/". url = URL(scope=scope) url = url.replace(path=url.path + "/") return RedirectResponse(url=url) return self.file_response(full_path, stat_result, scope) if self.html: # Check for '404.html' if we're in HTML mode. full_path, stat_result = await anyio.to_thread.run_sync( self.lookup_path, "404.html" ) if stat_result and stat.S_ISREG(stat_result.st_mode): return FileResponse( full_path, stat_result=stat_result, method=scope["method"], status_code=404, ) raise HTTPException(status_code=404) def lookup_path( self, path: str ) -> typing.Tuple[str, typing.Optional[os.stat_result]]: for directory in self.all_directories: full_path = os.path.realpath(os.path.join(directory, path)) directory = os.path.realpath(directory) if os.path.commonprefix([full_path, directory]) != directory: # Don't allow misbehaving clients to break out of the static files # directory. continue try: return full_path, os.stat(full_path) except (FileNotFoundError, NotADirectoryError): continue return "", None def file_response( self, full_path: PathLike, stat_result: os.stat_result, scope: Scope, status_code: int = 200, ) -> Response: method = scope["method"] request_headers = Headers(scope=scope) response = FileResponse( full_path, status_code=status_code, stat_result=stat_result, method=method ) if self.is_not_modified(response.headers, request_headers): return NotModifiedResponse(response.headers) return response async def check_config(self) -> None: """ Perform a one-off configuration check that StaticFiles is actually pointed at a directory, so that we can raise loud errors rather than just returning 404 responses. """ if self.directory is None: return try: stat_result = await anyio.to_thread.run_sync(os.stat, self.directory) except FileNotFoundError: raise RuntimeError( f"StaticFiles directory '{self.directory}' does not exist." ) if not (stat.S_ISDIR(stat_result.st_mode) or stat.S_ISLNK(stat_result.st_mode)): raise RuntimeError( f"StaticFiles path '{self.directory}' is not a directory." ) def is_not_modified( self, response_headers: Headers, request_headers: Headers ) -> bool: """ Given the request and response headers, return `True` if an HTTP "Not Modified" response could be returned instead. """ try: if_none_match = request_headers["if-none-match"] etag = response_headers["etag"] if if_none_match == etag: return True except KeyError: pass try: if_modified_since = parsedate(request_headers["if-modified-since"]) last_modified = parsedate(response_headers["last-modified"]) if ( if_modified_since is not None and last_modified is not None and if_modified_since >= last_modified ): return True except KeyError: pass return False