# -*- test-case-name: klein.test.test_resource -*- from __future__ import annotations from typing import TYPE_CHECKING, Any, Optional, Sequence, Tuple, Union, cast from werkzeug.exceptions import HTTPException from twisted.internet import defer from twisted.internet.defer import Deferred, maybeDeferred, succeed from twisted.python import log from twisted.python.failure import Failure from twisted.web import server from twisted.web.iweb import IRenderable, IRequest from twisted.web.resource import IResource, Resource, getChildForRequest from twisted.web.template import renderElement from ._dihttp import Response from ._interfaces import IKleinRequest if TYPE_CHECKING: # NB: circular import, must not be imported at runtime. from ._app import ( ErrorMethods, Klein, KleinRenderable, KleinRouteHandler, RouteMetadata, ) def route_metadata(handler: KleinRouteHandler) -> RouteMetadata: return handler # type:ignore[return-value] def ensure_utf8_bytes(v: Union[str, bytes]) -> bytes: """ Coerces a value which is either a C{str} or C{bytes} to a C{bytes}. If ``v`` is a C{str} object it is encoded as utf-8. """ if isinstance(v, str): v = v.encode("utf-8") return v class _StandInResource: """ A standin for a Resource. This is a sentinel value for L{KleinResource}, to say that we are rendering a L{Resource}, which may close the connection itself later. """ StandInResource = cast("KleinResource", _StandInResource()) class URLDecodeError(Exception): """ Raised if one or more string parts of the URL could not be decoded. """ __slots__ = ["errors"] def __init__(self, errors: Sequence[Tuple[str, Failure]]) -> None: """ @param errors: Sequence of decoding errors, expressed as tuples of names and an associated failure. """ self.errors = errors def __repr__(self) -> str: return f"" def extractURLparts(request: IRequest) -> Tuple[str, str, int, str, str]: """ Extracts and decodes URI parts from C{request}. All strings must be UTF8-decodable. @param request: A Twisted Web request. @raise URLDecodeError: If one of the parts could not be decoded as UTF-8. @return: L{tuple} of the URL scheme, the server name, the server port, the path info and the script name. """ server_name = request.getRequestHostname() if hasattr(request.getHost(), "port"): server_port = request.getHost().port else: server_port = 0 if (bool(request.isSecure()), server_port) not in [ (True, 443), (False, 80), (False, 0), (True, 0), ]: server_name = b"%s:%d" % (server_name, server_port) script_name = b"" if request.prepath: script_name = b"/".join(request.prepath) if not script_name.startswith(b"/"): script_name = b"/" + script_name path_info = b"" if request.postpath: path_info = b"/".join(request.postpath) if not path_info.startswith(b"/"): path_info = b"/" + path_info url_scheme = "https" if request.isSecure() else "http" utf8Failures = [] try: server_name = server_name.decode("utf-8") except UnicodeDecodeError: utf8Failures.append(("SERVER_NAME", Failure())) try: path_text = path_info.decode("utf-8") except UnicodeDecodeError: utf8Failures.append(("PATH_INFO", Failure())) try: script_text = script_name.decode("utf-8") except UnicodeDecodeError: utf8Failures.append(("SCRIPT_NAME", Failure())) if utf8Failures: raise URLDecodeError(utf8Failures) return url_scheme, server_name, server_port, path_text, script_text class KleinResource(Resource): """ A ``Resource`` that can do URL routing. """ isLeaf = True def __init__(self, app: Klein) -> None: super().__init__() self._app = app def __eq__(self, other: object) -> bool: if isinstance(other, KleinResource): return vars(self) == vars(other) return NotImplemented def __ne__(self, other: object) -> bool: result = self.__eq__(other) if result is NotImplemented: return result return not result def render(self, request: IRequest) -> KleinRenderable: # Stuff we need to know for the mapper. try: ( url_scheme, server_name, server_port, path_info, script_name, ) = extractURLparts(request) except URLDecodeError as e: for what, fail in e.errors: log.err(fail, f"Invalid encoding in {what}.") request.setResponseCode(400) return b"Non-UTF-8 encoding in URL." # Bind our mapper. mapper = self._app.url_map.bind( server_name, script_name, path_info=path_info, default_method=request.method.decode("utf-8"), url_scheme=url_scheme, ) # Make the mapper available to the view. kleinRequest = IKleinRequest(request) kleinRequest.mapper = mapper # Make sure we'll notice when the connection goes away unambiguously. request_finished = [False] def _finish(result: object) -> None: request_finished[0] = True def _execute() -> Deferred: # Actually doing the match right here. This can cause an exception # to percolate up. If that happens it will be handled below in # processing_failed, either by a user-registered error handler or # one of our defaults. (rule, kwargs) = mapper.match(return_rule=True) endpoint = rule.endpoint # Try pretty hard to fix up prepath and postpath. segment_count = route_metadata( self._app.endpoints[endpoint] ).segment_count request.prepath.extend(request.postpath[:segment_count]) request.postpath = request.postpath[segment_count:] request.notifyFinish().addBoth( # type: ignore[attr-defined] _finish, ) # Standard Twisted Web stuff. Defer the method action, giving us # something renderable or printable. Return NOT_DONE_YET and set up # the incremental renderer. d = maybeDeferred( self._app.execute_endpoint, endpoint, request, **kwargs ) request.notifyFinish().addErrback( # type: ignore[attr-defined] lambda _: d.cancel(), ) return d d = maybeDeferred(_execute) # typing note: returns Any because Response._applyToRequest returns Any def process(r: object) -> Any: """ Recursively go through r and any child Resources until something returns an IRenderable, then render it and let the result of that bubble back up. """ if isinstance(r, Response): r = r._applyToRequest(request) if IResource.providedBy(r): request.render( # type: ignore[attr-defined] getChildForRequest(r, request) ) return StandInResource if IRenderable.providedBy(r): renderElement(request, r) return StandInResource return r d.addCallback(process) def processing_failed( failure: Failure, error_handlers: ErrorMethods ) -> Optional[Deferred]: # The failure processor writes to the request. If the # request is already finished we should suppress failure # processing. We don't return failure here because there # is no way to surface this failure to the user if the # request is finished. if request_finished[0]: if not failure.check(defer.CancelledError): log.err(failure, "Unhandled Error Processing Request.") return None # If there are no more registered handlers, apply some defaults if len(error_handlers) == 0: if failure.check(HTTPException): he = failure.value assert isinstance(he, HTTPException) request.setResponseCode(he.code) resp = he.get_response({}) for header, value in resp.headers: request.setHeader( ensure_utf8_bytes(header), ensure_utf8_bytes(value) ) encoded = resp.iter_encoded() # type: ignore[attr-defined] return succeed(ensure_utf8_bytes(b"".join(encoded))) else: request.processingFailed( # type: ignore[attr-defined] failure, ) return None error_handler = error_handlers[0] # Each error handler is a tuple of # (list_of_exception_types, handler_fn) if failure.check(*error_handler[0]): handler_func = error_handler[1] d = maybeDeferred( self._app.execute_error_handler, handler_func, request, failure, ) d.addCallback(process) return d.addErrback(processing_failed, error_handlers[1:]) return processing_failed(failure, error_handlers[1:]) d.addErrback(processing_failed, self._app._error_handlers) def write_response( r: Union[_StandInResource, str, bytes, int, None] ) -> None: if r is StandInResource: return if isinstance(r, str): r = r.encode("utf-8") if isinstance(r, bytes): request.write(r) if not request_finished[0]: request.finish() d.addCallback(write_response) d.addErrback(log.err, _why="Unhandled Error writing response") return server.NOT_DONE_YET # type: ignore[return-value]