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synapse/synapse/http/site.py
Erik Johnston 334e075dd8 Fix error when logging incomplete requests
If a connection is lost before a request is read from Request, Twisted
sets `method` (and `uri`) attributes to dummy values. These dummy values
have incorrect types (i.e. they're not bytes), and so things like
`__repr__` would raise an exception.

To fix this we had a helper method to return the method with a
consistent type.
2018-10-02 12:06:22 +01:00

358 lines
13 KiB
Python

# Copyright 2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import contextlib
import logging
import time
from twisted.web.server import Request, Site
from synapse.http import redact_uri
from synapse.http.request_metrics import RequestMetrics, requests_counter
from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
logger = logging.getLogger(__name__)
_next_request_seq = 0
class SynapseRequest(Request):
"""Class which encapsulates an HTTP request to synapse.
All of the requests processed in synapse are of this type.
It extends twisted's twisted.web.server.Request, and adds:
* Unique request ID
* A log context associated with the request
* Redaction of access_token query-params in __repr__
* Logging at start and end
* Metrics to record CPU, wallclock and DB time by endpoint.
It also provides a method `processing`, which returns a context manager. If this
method is called, the request won't be logged until the context manager is closed;
this is useful for asynchronous request handlers which may go on processing the
request even after the client has disconnected.
Attributes:
logcontext(LoggingContext) : the log context for this request
"""
def __init__(self, site, channel, *args, **kw):
Request.__init__(self, channel, *args, **kw)
self.site = site
self._channel = channel # this is used by the tests
self.authenticated_entity = None
self.start_time = 0
# we can't yet create the logcontext, as we don't know the method.
self.logcontext = None
global _next_request_seq
self.request_seq = _next_request_seq
_next_request_seq += 1
# whether an asynchronous request handler has called processing()
self._is_processing = False
# the time when the asynchronous request handler completed its processing
self._processing_finished_time = None
# what time we finished sending the response to the client (or the connection
# dropped)
self.finish_time = None
def __repr__(self):
# We overwrite this so that we don't log ``access_token``
return '<%s at 0x%x method=%r uri=%r clientproto=%r site=%r>' % (
self.__class__.__name__,
id(self),
self.get_method(),
self.get_redacted_uri(),
self.clientproto.decode('ascii', errors='replace'),
self.site.site_tag,
)
def get_request_id(self):
return "%s-%i" % (self.get_method(), self.request_seq)
def get_redacted_uri(self):
uri = self.uri
if isinstance(uri, bytes):
uri = self.uri.decode('ascii')
return redact_uri(uri)
def get_method(self):
"""Gets the method associated with the request (or placeholder if not
method has yet been received).
Note: This is necessary as the placeholder value in twisted is str
rather than bytes, so we need to sanitise `self.method`.
Returns:
str
"""
method = self.method
if isinstance(method, bytes):
method = self.method.decode('ascii')
return method
def get_user_agent(self):
return self.requestHeaders.getRawHeaders(b"User-Agent", [None])[-1]
def render(self, resrc):
# this is called once a Resource has been found to serve the request; in our
# case the Resource in question will normally be a JsonResource.
# create a LogContext for this request
request_id = self.get_request_id()
logcontext = self.logcontext = LoggingContext(request_id)
logcontext.request = request_id
# override the Server header which is set by twisted
self.setHeader("Server", self.site.server_version_string)
with PreserveLoggingContext(self.logcontext):
# we start the request metrics timer here with an initial stab
# at the servlet name. For most requests that name will be
# JsonResource (or a subclass), and JsonResource._async_render
# will update it once it picks a servlet.
servlet_name = resrc.__class__.__name__
self._started_processing(servlet_name)
Request.render(self, resrc)
# record the arrival of the request *after*
# dispatching to the handler, so that the handler
# can update the servlet name in the request
# metrics
requests_counter.labels(self.get_method(),
self.request_metrics.name).inc()
@contextlib.contextmanager
def processing(self):
"""Record the fact that we are processing this request.
Returns a context manager; the correct way to use this is:
@defer.inlineCallbacks
def handle_request(request):
with request.processing("FooServlet"):
yield really_handle_the_request()
Once the context manager is closed, the completion of the request will be logged,
and the various metrics will be updated.
"""
if self._is_processing:
raise RuntimeError("Request is already processing")
self._is_processing = True
try:
yield
except Exception:
# this should already have been caught, and sent back to the client as a 500.
logger.exception("Asynchronous messge handler raised an uncaught exception")
finally:
# the request handler has finished its work and either sent the whole response
# back, or handed over responsibility to a Producer.
self._processing_finished_time = time.time()
self._is_processing = False
# if we've already sent the response, log it now; otherwise, we wait for the
# response to be sent.
if self.finish_time is not None:
self._finished_processing()
def finish(self):
"""Called when all response data has been written to this Request.
Overrides twisted.web.server.Request.finish to record the finish time and do
logging.
"""
self.finish_time = time.time()
Request.finish(self)
if not self._is_processing:
with PreserveLoggingContext(self.logcontext):
self._finished_processing()
def connectionLost(self, reason):
"""Called when the client connection is closed before the response is written.
Overrides twisted.web.server.Request.connectionLost to record the finish time and
do logging.
"""
self.finish_time = time.time()
Request.connectionLost(self, reason)
# we only get here if the connection to the client drops before we send
# the response.
#
# It's useful to log it here so that we can get an idea of when
# the client disconnects.
with PreserveLoggingContext(self.logcontext):
logger.warn(
"Error processing request %r: %s %s", self, reason.type, reason.value,
)
if not self._is_processing:
self._finished_processing()
def _started_processing(self, servlet_name):
"""Record the fact that we are processing this request.
This will log the request's arrival. Once the request completes,
be sure to call finished_processing.
Args:
servlet_name (str): the name of the servlet which will be
processing this request. This is used in the metrics.
It is possible to update this afterwards by updating
self.request_metrics.name.
"""
self.start_time = time.time()
self.request_metrics = RequestMetrics()
self.request_metrics.start(
self.start_time, name=servlet_name, method=self.get_method(),
)
self.site.access_logger.info(
"%s - %s - Received request: %s %s",
self.getClientIP(),
self.site.site_tag,
self.get_method(),
self.get_redacted_uri()
)
def _finished_processing(self):
"""Log the completion of this request and update the metrics
"""
if self.logcontext is None:
# this can happen if the connection closed before we read the
# headers (so render was never called). In that case we'll already
# have logged a warning, so just bail out.
return
usage = self.logcontext.get_resource_usage()
if self._processing_finished_time is None:
# we completed the request without anything calling processing()
self._processing_finished_time = time.time()
# the time between receiving the request and the request handler finishing
processing_time = self._processing_finished_time - self.start_time
# the time between the request handler finishing and the response being sent
# to the client (nb may be negative)
response_send_time = self.finish_time - self._processing_finished_time
# need to decode as it could be raw utf-8 bytes
# from a IDN servname in an auth header
authenticated_entity = self.authenticated_entity
if authenticated_entity is not None and isinstance(authenticated_entity, bytes):
authenticated_entity = authenticated_entity.decode("utf-8", "replace")
# ...or could be raw utf-8 bytes in the User-Agent header.
# N.B. if you don't do this, the logger explodes cryptically
# with maximum recursion trying to log errors about
# the charset problem.
# c.f. https://github.com/matrix-org/synapse/issues/3471
user_agent = self.get_user_agent()
if user_agent is not None:
user_agent = user_agent.decode("utf-8", "replace")
else:
user_agent = "-"
code = str(self.code)
if not self.finished:
# we didn't send the full response before we gave up (presumably because
# the connection dropped)
code += "!"
self.site.access_logger.info(
"%s - %s - {%s}"
" Processed request: %.3fsec/%.3fsec (%.3fsec, %.3fsec) (%.3fsec/%.3fsec/%d)"
" %sB %s \"%s %s %s\" \"%s\" [%d dbevts]",
self.getClientIP(),
self.site.site_tag,
authenticated_entity,
processing_time,
response_send_time,
usage.ru_utime,
usage.ru_stime,
usage.db_sched_duration_sec,
usage.db_txn_duration_sec,
int(usage.db_txn_count),
self.sentLength,
code,
self.get_method(),
self.get_redacted_uri(),
self.clientproto.decode('ascii', errors='replace'),
user_agent,
usage.evt_db_fetch_count,
)
try:
self.request_metrics.stop(self.finish_time, self.code, self.sentLength)
except Exception as e:
logger.warn("Failed to stop metrics: %r", e)
class XForwardedForRequest(SynapseRequest):
def __init__(self, *args, **kw):
SynapseRequest.__init__(self, *args, **kw)
"""
Add a layer on top of another request that only uses the value of an
X-Forwarded-For header as the result of C{getClientIP}.
"""
def getClientIP(self):
"""
@return: The client address (the first address) in the value of the
I{X-Forwarded-For header}. If the header is not present, return
C{b"-"}.
"""
return self.requestHeaders.getRawHeaders(
b"x-forwarded-for", [b"-"])[0].split(b",")[0].strip().decode('ascii')
class SynapseRequestFactory(object):
def __init__(self, site, x_forwarded_for):
self.site = site
self.x_forwarded_for = x_forwarded_for
def __call__(self, *args, **kwargs):
if self.x_forwarded_for:
return XForwardedForRequest(self.site, *args, **kwargs)
else:
return SynapseRequest(self.site, *args, **kwargs)
class SynapseSite(Site):
"""
Subclass of a twisted http Site that does access logging with python's
standard logging
"""
def __init__(self, logger_name, site_tag, config, resource,
server_version_string, *args, **kwargs):
Site.__init__(self, resource, *args, **kwargs)
self.site_tag = site_tag
proxied = config.get("x_forwarded", False)
self.requestFactory = SynapseRequestFactory(self, proxied)
self.access_logger = logging.getLogger(logger_name)
self.server_version_string = server_version_string.encode('ascii')
def log(self, request):
pass