751 lines
25 KiB
Python
751 lines
25 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2018 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import abc
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import collections
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import html
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import logging
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import types
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import urllib
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from http import HTTPStatus
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from io import BytesIO
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from typing import Any, Callable, Dict, Iterator, List, Tuple, Union
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import jinja2
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from canonicaljson import iterencode_canonical_json
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from zope.interface import implementer
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from twisted.internet import defer, interfaces
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from twisted.python import failure
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from twisted.web import resource
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from twisted.web.server import NOT_DONE_YET, Request
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from twisted.web.static import File, NoRangeStaticProducer
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from twisted.web.util import redirectTo
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from synapse.api.errors import (
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CodeMessageException,
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Codes,
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RedirectException,
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SynapseError,
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UnrecognizedRequestError,
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)
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from synapse.http.site import SynapseRequest
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from synapse.logging.context import preserve_fn
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from synapse.logging.opentracing import trace_servlet
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from synapse.util import json_encoder
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from synapse.util.caches import intern_dict
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logger = logging.getLogger(__name__)
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HTML_ERROR_TEMPLATE = """<!DOCTYPE html>
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<html lang=en>
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<head>
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<meta charset="utf-8">
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<title>Error {code}</title>
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</head>
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<body>
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<p>{msg}</p>
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</body>
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</html>
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"""
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def return_json_error(f: failure.Failure, request: SynapseRequest) -> None:
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"""Sends a JSON error response to clients.
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"""
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if f.check(SynapseError):
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error_code = f.value.code
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error_dict = f.value.error_dict()
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logger.info("%s SynapseError: %s - %s", request, error_code, f.value.msg)
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else:
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error_code = 500
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error_dict = {"error": "Internal server error", "errcode": Codes.UNKNOWN}
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logger.error(
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"Failed handle request via %r: %r",
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request.request_metrics.name,
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request,
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exc_info=(f.type, f.value, f.getTracebackObject()),
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)
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# Only respond with an error response if we haven't already started writing,
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# otherwise lets just kill the connection
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if request.startedWriting:
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if request.transport:
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try:
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request.transport.abortConnection()
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except Exception:
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# abortConnection throws if the connection is already closed
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pass
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else:
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respond_with_json(
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request, error_code, error_dict, send_cors=True,
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)
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def return_html_error(
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f: failure.Failure, request: Request, error_template: Union[str, jinja2.Template],
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) -> None:
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"""Sends an HTML error page corresponding to the given failure.
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Handles RedirectException and other CodeMessageExceptions (such as SynapseError)
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Args:
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f: the error to report
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request: the failing request
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error_template: the HTML template. Can be either a string (with `{code}`,
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`{msg}` placeholders), or a jinja2 template
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"""
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if f.check(CodeMessageException):
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cme = f.value
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code = cme.code
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msg = cme.msg
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if isinstance(cme, RedirectException):
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logger.info("%s redirect to %s", request, cme.location)
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request.setHeader(b"location", cme.location)
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request.cookies.extend(cme.cookies)
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elif isinstance(cme, SynapseError):
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logger.info("%s SynapseError: %s - %s", request, code, msg)
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else:
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logger.error(
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"Failed handle request %r",
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request,
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exc_info=(f.type, f.value, f.getTracebackObject()),
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)
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else:
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code = HTTPStatus.INTERNAL_SERVER_ERROR
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msg = "Internal server error"
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logger.error(
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"Failed handle request %r",
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request,
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exc_info=(f.type, f.value, f.getTracebackObject()),
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)
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if isinstance(error_template, str):
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body = error_template.format(code=code, msg=html.escape(msg))
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else:
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body = error_template.render(code=code, msg=msg)
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respond_with_html(request, code, body)
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def wrap_async_request_handler(h):
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"""Wraps an async request handler so that it calls request.processing.
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This helps ensure that work done by the request handler after the request is completed
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is correctly recorded against the request metrics/logs.
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The handler method must have a signature of "handle_foo(self, request)",
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where "request" must be a SynapseRequest.
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The handler may return a deferred, in which case the completion of the request isn't
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logged until the deferred completes.
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"""
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async def wrapped_async_request_handler(self, request):
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with request.processing():
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await h(self, request)
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# we need to preserve_fn here, because the synchronous render method won't yield for
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# us (obviously)
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return preserve_fn(wrapped_async_request_handler)
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class HttpServer:
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""" Interface for registering callbacks on a HTTP server
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"""
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def register_paths(self, method, path_patterns, callback):
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""" Register a callback that gets fired if we receive a http request
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with the given method for a path that matches the given regex.
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If the regex contains groups these gets passed to the callback via
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an unpacked tuple.
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Args:
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method (str): The method to listen to.
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path_patterns (list<SRE_Pattern>): The regex used to match requests.
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callback (function): The function to fire if we receive a matched
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request. The first argument will be the request object and
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subsequent arguments will be any matched groups from the regex.
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This should return a tuple of (code, response).
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"""
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pass
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class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
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"""Base class for resources that have async handlers.
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Sub classes can either implement `_async_render_<METHOD>` to handle
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requests by method, or override `_async_render` to handle all requests.
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Args:
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extract_context: Whether to attempt to extract the opentracing
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context from the request the servlet is handling.
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"""
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def __init__(self, extract_context=False):
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super().__init__()
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self._extract_context = extract_context
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def render(self, request):
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""" This gets called by twisted every time someone sends us a request.
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"""
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defer.ensureDeferred(self._async_render_wrapper(request))
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return NOT_DONE_YET
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@wrap_async_request_handler
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async def _async_render_wrapper(self, request: SynapseRequest):
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"""This is a wrapper that delegates to `_async_render` and handles
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exceptions, return values, metrics, etc.
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"""
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try:
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request.request_metrics.name = self.__class__.__name__
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with trace_servlet(request, self._extract_context):
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callback_return = await self._async_render(request)
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if callback_return is not None:
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code, response = callback_return
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self._send_response(request, code, response)
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except Exception:
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# failure.Failure() fishes the original Failure out
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# of our stack, and thus gives us a sensible stack
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# trace.
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f = failure.Failure()
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self._send_error_response(f, request)
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async def _async_render(self, request: Request):
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"""Delegates to `_async_render_<METHOD>` methods, or returns a 400 if
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no appropriate method exists. Can be overridden in sub classes for
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different routing.
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"""
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# Treat HEAD requests as GET requests.
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request_method = request.method.decode("ascii")
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if request_method == "HEAD":
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request_method = "GET"
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method_handler = getattr(self, "_async_render_%s" % (request_method,), None)
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if method_handler:
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raw_callback_return = method_handler(request)
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# Is it synchronous? We'll allow this for now.
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if isinstance(raw_callback_return, (defer.Deferred, types.CoroutineType)):
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callback_return = await raw_callback_return
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else:
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callback_return = raw_callback_return # type: ignore
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return callback_return
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_unrecognised_request_handler(request)
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@abc.abstractmethod
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def _send_response(
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self, request: SynapseRequest, code: int, response_object: Any,
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) -> None:
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raise NotImplementedError()
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@abc.abstractmethod
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def _send_error_response(
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self, f: failure.Failure, request: SynapseRequest,
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) -> None:
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raise NotImplementedError()
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class DirectServeJsonResource(_AsyncResource):
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"""A resource that will call `self._async_on_<METHOD>` on new requests,
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formatting responses and errors as JSON.
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"""
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def _send_response(
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self, request: Request, code: int, response_object: Any,
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):
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"""Implements _AsyncResource._send_response
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"""
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# TODO: Only enable CORS for the requests that need it.
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respond_with_json(
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request,
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code,
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response_object,
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send_cors=True,
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canonical_json=self.canonical_json,
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)
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def _send_error_response(
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self, f: failure.Failure, request: SynapseRequest,
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) -> None:
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"""Implements _AsyncResource._send_error_response
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"""
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return_json_error(f, request)
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class JsonResource(DirectServeJsonResource):
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""" This implements the HttpServer interface and provides JSON support for
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Resources.
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Register callbacks via register_paths()
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Callbacks can return a tuple of status code and a dict in which case the
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the dict will automatically be sent to the client as a JSON object.
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The JsonResource is primarily intended for returning JSON, but callbacks
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may send something other than JSON, they may do so by using the methods
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on the request object and instead returning None.
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"""
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isLeaf = True
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_PathEntry = collections.namedtuple(
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"_PathEntry", ["pattern", "callback", "servlet_classname"]
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)
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def __init__(self, hs, canonical_json=True, extract_context=False):
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super().__init__(extract_context)
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self.canonical_json = canonical_json
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self.clock = hs.get_clock()
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self.path_regexs = {}
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self.hs = hs
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def register_paths(self, method, path_patterns, callback, servlet_classname):
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"""
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Registers a request handler against a regular expression. Later request URLs are
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checked against these regular expressions in order to identify an appropriate
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handler for that request.
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Args:
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method (str): GET, POST etc
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path_patterns (Iterable[str]): A list of regular expressions to which
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the request URLs are compared.
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callback (function): The handler for the request. Usually a Servlet
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servlet_classname (str): The name of the handler to be used in prometheus
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and opentracing logs.
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"""
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method = method.encode("utf-8") # method is bytes on py3
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for path_pattern in path_patterns:
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logger.debug("Registering for %s %s", method, path_pattern.pattern)
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self.path_regexs.setdefault(method, []).append(
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self._PathEntry(path_pattern, callback, servlet_classname)
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)
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def _get_handler_for_request(
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self, request: SynapseRequest
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) -> Tuple[Callable, str, Dict[str, str]]:
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"""Finds a callback method to handle the given request.
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Returns:
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A tuple of the callback to use, the name of the servlet, and the
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key word arguments to pass to the callback
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"""
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# Treat HEAD requests as GET requests.
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request_path = request.path.decode("ascii")
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request_method = request.method
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if request_method == b"HEAD":
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request_method = b"GET"
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# Loop through all the registered callbacks to check if the method
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# and path regex match
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for path_entry in self.path_regexs.get(request_method, []):
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m = path_entry.pattern.match(request_path)
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if m:
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# We found a match!
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return path_entry.callback, path_entry.servlet_classname, m.groupdict()
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# Huh. No one wanted to handle that? Fiiiiiine. Send 400.
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return _unrecognised_request_handler, "unrecognised_request_handler", {}
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async def _async_render(self, request):
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callback, servlet_classname, group_dict = self._get_handler_for_request(request)
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# Make sure we have an appropriate name for this handler in prometheus
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# (rather than the default of JsonResource).
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request.request_metrics.name = servlet_classname
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# Now trigger the callback. If it returns a response, we send it
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# here. If it throws an exception, that is handled by the wrapper
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# installed by @request_handler.
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kwargs = intern_dict(
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{
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name: urllib.parse.unquote(value) if value else value
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for name, value in group_dict.items()
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}
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)
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raw_callback_return = callback(request, **kwargs)
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# Is it synchronous? We'll allow this for now.
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if isinstance(raw_callback_return, (defer.Deferred, types.CoroutineType)):
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callback_return = await raw_callback_return
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else:
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callback_return = raw_callback_return # type: ignore
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return callback_return
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class DirectServeHtmlResource(_AsyncResource):
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"""A resource that will call `self._async_on_<METHOD>` on new requests,
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formatting responses and errors as HTML.
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"""
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# The error template to use for this resource
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ERROR_TEMPLATE = HTML_ERROR_TEMPLATE
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def _send_response(
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self, request: SynapseRequest, code: int, response_object: Any,
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):
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"""Implements _AsyncResource._send_response
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"""
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# We expect to get bytes for us to write
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assert isinstance(response_object, bytes)
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html_bytes = response_object
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respond_with_html_bytes(request, 200, html_bytes)
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def _send_error_response(
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self, f: failure.Failure, request: SynapseRequest,
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) -> None:
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"""Implements _AsyncResource._send_error_response
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"""
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return_html_error(f, request, self.ERROR_TEMPLATE)
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class StaticResource(File):
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"""
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A resource that represents a plain non-interpreted file or directory.
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Differs from the File resource by adding clickjacking protection.
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"""
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def render_GET(self, request: Request):
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set_clickjacking_protection_headers(request)
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return super().render_GET(request)
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def _unrecognised_request_handler(request):
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"""Request handler for unrecognised requests
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This is a request handler suitable for return from
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_get_handler_for_request. It actually just raises an
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UnrecognizedRequestError.
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Args:
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request (twisted.web.http.Request):
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"""
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raise UnrecognizedRequestError()
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class RootRedirect(resource.Resource):
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"""Redirects the root '/' path to another path."""
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def __init__(self, path):
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resource.Resource.__init__(self)
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self.url = path
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def render_GET(self, request):
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return redirectTo(self.url.encode("ascii"), request)
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def getChild(self, name, request):
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if len(name) == 0:
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return self # select ourselves as the child to render
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return resource.Resource.getChild(self, name, request)
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class OptionsResource(resource.Resource):
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"""Responds to OPTION requests for itself and all children."""
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def render_OPTIONS(self, request):
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request.setResponseCode(204)
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request.setHeader(b"Content-Length", b"0")
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set_cors_headers(request)
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return b""
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def getChildWithDefault(self, path, request):
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if request.method == b"OPTIONS":
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return self # select ourselves as the child to render
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return resource.Resource.getChildWithDefault(self, path, request)
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class RootOptionsRedirectResource(OptionsResource, RootRedirect):
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pass
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@implementer(interfaces.IPushProducer)
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class _ByteProducer:
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"""
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Iteratively write bytes to the request.
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"""
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# The minimum number of bytes for each chunk. Note that the last chunk will
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# usually be smaller than this.
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min_chunk_size = 1024
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def __init__(
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self, request: Request, iterator: Iterator[bytes],
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):
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self._request = request
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self._iterator = iterator
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self._paused = False
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# Register the producer and start producing data.
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self._request.registerProducer(self, True)
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self.resumeProducing()
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def _send_data(self, data: List[bytes]) -> None:
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"""
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Send a list of bytes as a chunk of a response.
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"""
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if not data:
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return
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self._request.write(b"".join(data))
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def pauseProducing(self) -> None:
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self._paused = True
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def resumeProducing(self) -> None:
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# We've stopped producing in the meantime (note that this might be
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# re-entrant after calling write).
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if not self._request:
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return
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self._paused = False
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# Write until there's backpressure telling us to stop.
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while not self._paused:
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# Get the next chunk and write it to the request.
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#
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# The output of the JSON encoder is buffered and coalesced until
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# min_chunk_size is reached. This is because JSON encoders produce
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# very small output per iteration and the Request object converts
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# each call to write() to a separate chunk. Without this there would
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# be an explosion in bytes written (e.g. b"{" becoming "1\r\n{\r\n").
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#
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# Note that buffer stores a list of bytes (instead of appending to
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# bytes) to hopefully avoid many allocations.
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buffer = []
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buffered_bytes = 0
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while buffered_bytes < self.min_chunk_size:
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try:
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data = next(self._iterator)
|
|
buffer.append(data)
|
|
buffered_bytes += len(data)
|
|
except StopIteration:
|
|
# The entire JSON object has been serialized, write any
|
|
# remaining data, finalize the producer and the request, and
|
|
# clean-up any references.
|
|
self._send_data(buffer)
|
|
self._request.unregisterProducer()
|
|
self._request.finish()
|
|
self.stopProducing()
|
|
return
|
|
|
|
self._send_data(buffer)
|
|
|
|
def stopProducing(self) -> None:
|
|
# Clear a circular reference.
|
|
self._request = None
|
|
|
|
|
|
def _encode_json_bytes(json_object: Any) -> Iterator[bytes]:
|
|
"""
|
|
Encode an object into JSON. Returns an iterator of bytes.
|
|
"""
|
|
for chunk in json_encoder.iterencode(json_object):
|
|
yield chunk.encode("utf-8")
|
|
|
|
|
|
def respond_with_json(
|
|
request: Request,
|
|
code: int,
|
|
json_object: Any,
|
|
send_cors: bool = False,
|
|
canonical_json: bool = True,
|
|
):
|
|
"""Sends encoded JSON in response to the given request.
|
|
|
|
Args:
|
|
request: The http request to respond to.
|
|
code: The HTTP response code.
|
|
json_object: The object to serialize to JSON.
|
|
send_cors: Whether to send Cross-Origin Resource Sharing headers
|
|
https://fetch.spec.whatwg.org/#http-cors-protocol
|
|
canonical_json: Whether to use the canonicaljson algorithm when encoding
|
|
the JSON bytes.
|
|
|
|
Returns:
|
|
twisted.web.server.NOT_DONE_YET if the request is still active.
|
|
"""
|
|
# could alternatively use request.notifyFinish() and flip a flag when
|
|
# the Deferred fires, but since the flag is RIGHT THERE it seems like
|
|
# a waste.
|
|
if request._disconnected:
|
|
logger.warning(
|
|
"Not sending response to request %s, already disconnected.", request
|
|
)
|
|
return None
|
|
|
|
if canonical_json:
|
|
encoder = iterencode_canonical_json
|
|
else:
|
|
encoder = _encode_json_bytes
|
|
|
|
request.setResponseCode(code)
|
|
request.setHeader(b"Content-Type", b"application/json")
|
|
request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
|
|
|
|
if send_cors:
|
|
set_cors_headers(request)
|
|
|
|
_ByteProducer(request, encoder(json_object))
|
|
return NOT_DONE_YET
|
|
|
|
|
|
def respond_with_json_bytes(
|
|
request: Request, code: int, json_bytes: bytes, send_cors: bool = False,
|
|
):
|
|
"""Sends encoded JSON in response to the given request.
|
|
|
|
Args:
|
|
request: The http request to respond to.
|
|
code: The HTTP response code.
|
|
json_bytes: The json bytes to use as the response body.
|
|
send_cors: Whether to send Cross-Origin Resource Sharing headers
|
|
https://fetch.spec.whatwg.org/#http-cors-protocol
|
|
|
|
Returns:
|
|
twisted.web.server.NOT_DONE_YET if the request is still active.
|
|
"""
|
|
if request._disconnected:
|
|
logger.warning(
|
|
"Not sending response to request %s, already disconnected.", request
|
|
)
|
|
return
|
|
|
|
request.setResponseCode(code)
|
|
request.setHeader(b"Content-Type", b"application/json")
|
|
request.setHeader(b"Content-Length", b"%d" % (len(json_bytes),))
|
|
request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
|
|
|
|
if send_cors:
|
|
set_cors_headers(request)
|
|
|
|
# note that this is zero-copy (the bytesio shares a copy-on-write buffer with
|
|
# the original `bytes`).
|
|
bytes_io = BytesIO(json_bytes)
|
|
|
|
producer = NoRangeStaticProducer(request, bytes_io)
|
|
producer.start()
|
|
return NOT_DONE_YET
|
|
|
|
|
|
def set_cors_headers(request: Request):
|
|
"""Set the CORS headers so that javascript running in a web browsers can
|
|
use this API
|
|
|
|
Args:
|
|
request: The http request to add CORS to.
|
|
"""
|
|
request.setHeader(b"Access-Control-Allow-Origin", b"*")
|
|
request.setHeader(
|
|
b"Access-Control-Allow-Methods", b"GET, HEAD, POST, PUT, DELETE, OPTIONS"
|
|
)
|
|
request.setHeader(
|
|
b"Access-Control-Allow-Headers",
|
|
b"Origin, X-Requested-With, Content-Type, Accept, Authorization, Date",
|
|
)
|
|
|
|
|
|
def respond_with_html(request: Request, code: int, html: str):
|
|
"""
|
|
Wraps `respond_with_html_bytes` by first encoding HTML from a str to UTF-8 bytes.
|
|
"""
|
|
respond_with_html_bytes(request, code, html.encode("utf-8"))
|
|
|
|
|
|
def respond_with_html_bytes(request: Request, code: int, html_bytes: bytes):
|
|
"""
|
|
Sends HTML (encoded as UTF-8 bytes) as the response to the given request.
|
|
|
|
Note that this adds clickjacking protection headers and finishes the request.
|
|
|
|
Args:
|
|
request: The http request to respond to.
|
|
code: The HTTP response code.
|
|
html_bytes: The HTML bytes to use as the response body.
|
|
"""
|
|
# could alternatively use request.notifyFinish() and flip a flag when
|
|
# the Deferred fires, but since the flag is RIGHT THERE it seems like
|
|
# a waste.
|
|
if request._disconnected:
|
|
logger.warning(
|
|
"Not sending response to request %s, already disconnected.", request
|
|
)
|
|
return
|
|
|
|
request.setResponseCode(code)
|
|
request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
|
|
request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
|
|
|
|
# Ensure this content cannot be embedded.
|
|
set_clickjacking_protection_headers(request)
|
|
|
|
request.write(html_bytes)
|
|
finish_request(request)
|
|
|
|
|
|
def set_clickjacking_protection_headers(request: Request):
|
|
"""
|
|
Set headers to guard against clickjacking of embedded content.
|
|
|
|
This sets the X-Frame-Options and Content-Security-Policy headers which instructs
|
|
browsers to not allow the HTML of the response to be embedded onto another
|
|
page.
|
|
|
|
Args:
|
|
request: The http request to add the headers to.
|
|
"""
|
|
request.setHeader(b"X-Frame-Options", b"DENY")
|
|
request.setHeader(b"Content-Security-Policy", b"frame-ancestors 'none';")
|
|
|
|
|
|
def finish_request(request: Request):
|
|
""" Finish writing the response to the request.
|
|
|
|
Twisted throws a RuntimeException if the connection closed before the
|
|
response was written but doesn't provide a convenient or reliable way to
|
|
determine if the connection was closed. So we catch and log the RuntimeException
|
|
|
|
You might think that ``request.notifyFinish`` could be used to tell if the
|
|
request was finished. However the deferred it returns won't fire if the
|
|
connection was already closed, meaning we'd have to have called the method
|
|
right at the start of the request. By the time we want to write the response
|
|
it will already be too late.
|
|
"""
|
|
try:
|
|
request.finish()
|
|
except RuntimeError as e:
|
|
logger.info("Connection disconnected before response was written: %r", e)
|