527 lines
18 KiB
Python
527 lines
18 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 cgi
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import collections
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import http.client
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import logging
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import types
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import urllib
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from io import BytesIO
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from canonicaljson import encode_canonical_json, encode_pretty_printed_json, json
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from twisted.internet import defer
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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
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from twisted.web.static import NoRangeStaticProducer
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from twisted.web.util import redirectTo
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import synapse.events
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import synapse.metrics
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from synapse.api.errors import (
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CodeMessageException,
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Codes,
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SynapseError,
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UnrecognizedRequestError,
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)
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from synapse.logging.context import preserve_fn
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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 wrap_json_request_handler(h):
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"""Wraps a request handler method with exception handling.
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Also does the wrapping with request.processing as per wrap_async_request_handler.
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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 must return a deferred or a coroutine. If the deferred succeeds
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we assume that a response has been sent. If the deferred fails with a SynapseError we use
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it to send a JSON response with the appropriate HTTP reponse code. If the
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deferred fails with any other type of error we send a 500 reponse.
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"""
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async def wrapped_request_handler(self, request):
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try:
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await h(self, request)
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except SynapseError as e:
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code = e.code
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logger.info("%s SynapseError: %s - %s", request, code, e.msg)
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# Only respond with an error response if we haven't already started
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# writing, 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,
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code,
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e.error_dict(),
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send_cors=True,
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pretty_print=_request_user_agent_is_curl(request),
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)
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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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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
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# writing, 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,
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500,
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{"error": "Internal server error", "errcode": Codes.UNKNOWN},
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send_cors=True,
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pretty_print=_request_user_agent_is_curl(request),
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)
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return wrap_async_request_handler(wrapped_request_handler)
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def wrap_html_request_handler(h):
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"""Wraps a request handler method with exception handling.
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Also does the wrapping with request.processing as per wrap_async_request_handler.
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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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"""
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async def wrapped_request_handler(self, request):
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try:
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return await h(self, request)
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except Exception:
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f = failure.Failure()
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return _return_html_error(f, request)
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return wrap_async_request_handler(wrapped_request_handler)
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def _return_html_error(f, request):
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"""Sends an HTML error page corresponding to the given failure
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Args:
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f (twisted.python.failure.Failure):
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request (twisted.web.iweb.IRequest):
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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, 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 = http.client.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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body = HTML_ERROR_TEMPLATE.format(code=code, msg=cgi.escape(msg)).encode("utf-8")
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request.setResponseCode(code)
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request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
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request.setHeader(b"Content-Length", b"%i" % (len(body),))
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request.write(body)
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finish_request(request)
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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(object):
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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 calback 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 JsonResource(HttpServer, resource.Resource):
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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("_PathEntry", ["pattern", "callback"])
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def __init__(self, hs, canonical_json=True):
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resource.Resource.__init__(self)
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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):
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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)
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)
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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(request))
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return NOT_DONE_YET
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@wrap_json_request_handler
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async def _async_render(self, request):
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""" This gets called from render() every time someone sends us a request.
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This checks if anyone has registered a callback for that method and
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path.
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"""
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callback, group_dict = self._get_handler_for_request(request)
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servlet_instance = getattr(callback, "__self__", None)
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if servlet_instance is not None:
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servlet_classname = servlet_instance.__class__.__name__
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else:
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servlet_classname = "%r" % callback
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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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callback_return = callback(request, **kwargs)
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# Is it synchronous? We'll allow this for now.
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if isinstance(callback_return, (defer.Deferred, types.CoroutineType)):
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callback_return = await callback_return
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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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def _get_handler_for_request(self, request):
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"""Finds a callback method to handle the given request
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Args:
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request (twisted.web.http.Request):
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Returns:
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Tuple[Callable, dict[unicode, unicode]]: callback method, and the
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dict mapping keys to path components as specified in the
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handler's path match regexp.
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The callback will normally be a method registered via
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register_paths, so will return (possibly via Deferred) either
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None, or a tuple of (http code, response body).
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"""
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if request.method == b"OPTIONS":
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return _options_handler, {}
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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.decode("ascii"))
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if m:
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# We found a match!
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return path_entry.callback, m.groupdict()
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# Huh. No one wanted to handle that? Fiiiiiine. Send 400.
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return _unrecognised_request_handler, {}
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def _send_response(
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self, request, code, response_json_object, response_code_message=None
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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_json_object,
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send_cors=True,
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response_code_message=response_code_message,
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pretty_print=_request_user_agent_is_curl(request),
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canonical_json=self.canonical_json,
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)
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class DirectServeResource(resource.Resource):
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def render(self, request):
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"""
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Render the request, using an asynchronous render handler if it exists.
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"""
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async_render_callback_name = "_async_render_" + request.method.decode("ascii")
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# Try and get the async renderer
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callback = getattr(self, async_render_callback_name, None)
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# No async renderer for this request method.
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if not callback:
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return super().render(request)
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resp = callback(request)
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# If it's a coroutine, turn it into a Deferred
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if isinstance(resp, types.CoroutineType):
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defer.ensureDeferred(resp)
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return NOT_DONE_YET
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def _options_handler(request):
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"""Request handler for OPTIONS requests
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This is a request handler suitable for return from
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_get_handler_for_request. It returns a 200 and an empty body.
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Args:
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request (twisted.web.http.Request):
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Returns:
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Tuple[int, dict]: http code, response body.
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"""
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return 200, {}
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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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def respond_with_json(
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request,
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code,
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json_object,
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send_cors=False,
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response_code_message=None,
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pretty_print=False,
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canonical_json=True,
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):
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# could alternatively use request.notifyFinish() and flip a flag when
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# the Deferred fires, but since the flag is RIGHT THERE it seems like
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# a waste.
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if request._disconnected:
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logger.warn(
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"Not sending response to request %s, already disconnected.", request
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)
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return
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if pretty_print:
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json_bytes = encode_pretty_printed_json(json_object) + b"\n"
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else:
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if canonical_json or synapse.events.USE_FROZEN_DICTS:
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# canonicaljson already encodes to bytes
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json_bytes = encode_canonical_json(json_object)
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else:
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json_bytes = json.dumps(json_object).encode("utf-8")
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return respond_with_json_bytes(
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request,
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code,
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json_bytes,
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send_cors=send_cors,
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response_code_message=response_code_message,
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)
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def respond_with_json_bytes(
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request, code, json_bytes, send_cors=False, response_code_message=None
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):
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"""Sends encoded JSON in response to the given request.
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Args:
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request (twisted.web.http.Request): The http request to respond to.
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code (int): The HTTP response code.
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json_bytes (bytes): The json bytes to use as the response body.
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send_cors (bool): Whether to send Cross-Origin Resource Sharing headers
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http://www.w3.org/TR/cors/
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Returns:
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twisted.web.server.NOT_DONE_YET"""
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request.setResponseCode(code, message=response_code_message)
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request.setHeader(b"Content-Type", b"application/json")
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request.setHeader(b"Content-Length", b"%d" % (len(json_bytes),))
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request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
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if send_cors:
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set_cors_headers(request)
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# todo: we can almost certainly avoid this copy and encode the json straight into
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# the bytesIO, but it would involve faffing around with string->bytes wrappers.
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bytes_io = BytesIO(json_bytes)
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producer = NoRangeStaticProducer(request, bytes_io)
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producer.start()
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return NOT_DONE_YET
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def set_cors_headers(request):
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"""Set the CORs headers so that javascript running in a web browsers can
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use this API
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Args:
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request (twisted.web.http.Request): The http request to add CORs to.
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"""
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request.setHeader(b"Access-Control-Allow-Origin", b"*")
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request.setHeader(
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b"Access-Control-Allow-Methods", b"GET, POST, PUT, DELETE, OPTIONS"
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)
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request.setHeader(
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b"Access-Control-Allow-Headers",
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b"Origin, X-Requested-With, Content-Type, Accept, Authorization",
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)
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def finish_request(request):
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""" Finish writing the response to the request.
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Twisted throws a RuntimeException if the connection closed before the
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response was written but doesn't provide a convenient or reliable way to
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determine if the connection was closed. So we catch and log the RuntimeException
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You might think that ``request.notifyFinish`` could be used to tell if the
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request was finished. However the deferred it returns won't fire if the
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connection was already closed, meaning we'd have to have called the method
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right at the start of the request. By the time we want to write the response
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it will already be too late.
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"""
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try:
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request.finish()
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except RuntimeError as e:
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logger.info("Connection disconnected before response was written: %r", e)
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def _request_user_agent_is_curl(request):
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user_agents = request.requestHeaders.getRawHeaders(b"User-Agent", default=[])
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for user_agent in user_agents:
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if b"curl" in user_agent:
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return True
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return False
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