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anonymousland-synapse/synapse/http/client.py
Richard van der Hoff 1c262431f9
Fix handling of connection timeouts in outgoing http requests (#8400) 
* Remove `on_timeout_cancel` from `timeout_deferred`

The `on_timeout_cancel` param to `timeout_deferred` wasn't always called on a
timeout (in particular if the canceller raised an exception), so it was
unreliable. It was also only used in one place, and to be honest it's easier to
do what it does a different way.

* Fix handling of connection timeouts in outgoing http requests

Turns out that if we get a timeout during connection, then a different
exception is raised, which wasn't always handled correctly.

To fix it, catch the exception in SimpleHttpClient and turn it into a
RequestTimedOutError (which is already a documented exception).

Also add a description to RequestTimedOutError so that we can see which stage
it failed at.

* Fix incorrect handling of timeouts reading federation responses

This was trapping the wrong sort of TimeoutError, so was never being hit.

The effect was relatively minor, but we should fix this so that it does the
expected thing.

* Fix inconsistent handling of `timeout` param between methods

`get_json`, `put_json` and `delete_json` were applying a different timeout to
the response body to `post_json`; bring them in line and test.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
Co-authored-by: Erik Johnston <erik@matrix.org>
2020-09-29 10:29:21 +01:00

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# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2018 New Vector 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 logging
import urllib
from io import BytesIO
from typing import (
Any,
BinaryIO,
Dict,
Iterable,
List,
Mapping,
Optional,
Sequence,
Tuple,
Union,
)
import treq
from canonicaljson import encode_canonical_json
from netaddr import IPAddress
from prometheus_client import Counter
from zope.interface import implementer, provider
from OpenSSL import SSL
from OpenSSL.SSL import VERIFY_NONE
from twisted.internet import defer, error as twisted_error, protocol, ssl
from twisted.internet.interfaces import (
IReactorPluggableNameResolver,
IResolutionReceiver,
)
from twisted.internet.task import Cooperator
from twisted.python.failure import Failure
from twisted.web._newclient import ResponseDone
from twisted.web.client import (
Agent,
HTTPConnectionPool,
ResponseNeverReceived,
readBody,
)
from twisted.web.http import PotentialDataLoss
from twisted.web.http_headers import Headers
from twisted.web.iweb import IResponse
from synapse.api.errors import Codes, HttpResponseException, SynapseError
from synapse.http import QuieterFileBodyProducer, RequestTimedOutError, redact_uri
from synapse.http.proxyagent import ProxyAgent
from synapse.logging.context import make_deferred_yieldable
from synapse.logging.opentracing import set_tag, start_active_span, tags
from synapse.util import json_decoder
from synapse.util.async_helpers import timeout_deferred
logger = logging.getLogger(__name__)
outgoing_requests_counter = Counter("synapse_http_client_requests", "", ["method"])
incoming_responses_counter = Counter(
"synapse_http_client_responses", "", ["method", "code"]
)
# the type of the headers list, to be passed to the t.w.h.Headers.
# Actually we can mix str and bytes keys, but Mapping treats 'key' as invariant so
# we simplify.
RawHeaders = Union[Mapping[str, "RawHeaderValue"], Mapping[bytes, "RawHeaderValue"]]
# the value actually has to be a List, but List is invariant so we can't specify that
# the entries can either be Lists or bytes.
RawHeaderValue = Sequence[Union[str, bytes]]
# the type of the query params, to be passed into `urlencode`
QueryParamValue = Union[str, bytes, Iterable[Union[str, bytes]]]
QueryParams = Union[Mapping[str, QueryParamValue], Mapping[bytes, QueryParamValue]]
def check_against_blacklist(ip_address, ip_whitelist, ip_blacklist):
"""
Args:
ip_address (netaddr.IPAddress)
ip_whitelist (netaddr.IPSet)
ip_blacklist (netaddr.IPSet)
"""
if ip_address in ip_blacklist:
if ip_whitelist is None or ip_address not in ip_whitelist:
return True
return False
_EPSILON = 0.00000001
def _make_scheduler(reactor):
"""Makes a schedular suitable for a Cooperator using the given reactor.
(This is effectively just a copy from `twisted.internet.task`)
"""
def _scheduler(x):
return reactor.callLater(_EPSILON, x)
return _scheduler
class IPBlacklistingResolver:
"""
A proxy for reactor.nameResolver which only produces non-blacklisted IP
addresses, preventing DNS rebinding attacks on URL preview.
"""
def __init__(self, reactor, ip_whitelist, ip_blacklist):
"""
Args:
reactor (twisted.internet.reactor)
ip_whitelist (netaddr.IPSet)
ip_blacklist (netaddr.IPSet)
"""
self._reactor = reactor
self._ip_whitelist = ip_whitelist
self._ip_blacklist = ip_blacklist
def resolveHostName(self, recv, hostname, portNumber=0):
r = recv()
addresses = []
def _callback():
r.resolutionBegan(None)
has_bad_ip = False
for i in addresses:
ip_address = IPAddress(i.host)
if check_against_blacklist(
ip_address, self._ip_whitelist, self._ip_blacklist
):
logger.info(
"Dropped %s from DNS resolution to %s due to blacklist"
% (ip_address, hostname)
)
has_bad_ip = True
# if we have a blacklisted IP, we'd like to raise an error to block the
# request, but all we can really do from here is claim that there were no
# valid results.
if not has_bad_ip:
for i in addresses:
r.addressResolved(i)
r.resolutionComplete()
@provider(IResolutionReceiver)
class EndpointReceiver:
@staticmethod
def resolutionBegan(resolutionInProgress):
pass
@staticmethod
def addressResolved(address):
addresses.append(address)
@staticmethod
def resolutionComplete():
_callback()
self._reactor.nameResolver.resolveHostName(
EndpointReceiver, hostname, portNumber=portNumber
)
return r
class BlacklistingAgentWrapper(Agent):
"""
An Agent wrapper which will prevent access to IP addresses being accessed
directly (without an IP address lookup).
"""
def __init__(self, agent, reactor, ip_whitelist=None, ip_blacklist=None):
"""
Args:
agent (twisted.web.client.Agent): The Agent to wrap.
reactor (twisted.internet.reactor)
ip_whitelist (netaddr.IPSet)
ip_blacklist (netaddr.IPSet)
"""
self._agent = agent
self._ip_whitelist = ip_whitelist
self._ip_blacklist = ip_blacklist
def request(self, method, uri, headers=None, bodyProducer=None):
h = urllib.parse.urlparse(uri.decode("ascii"))
try:
ip_address = IPAddress(h.hostname)
if check_against_blacklist(
ip_address, self._ip_whitelist, self._ip_blacklist
):
logger.info("Blocking access to %s due to blacklist" % (ip_address,))
e = SynapseError(403, "IP address blocked by IP blacklist entry")
return defer.fail(Failure(e))
except Exception:
# Not an IP
pass
return self._agent.request(
method, uri, headers=headers, bodyProducer=bodyProducer
)
class SimpleHttpClient:
"""
A simple, no-frills HTTP client with methods that wrap up common ways of
using HTTP in Matrix
"""
def __init__(
self,
hs,
treq_args={},
ip_whitelist=None,
ip_blacklist=None,
http_proxy=None,
https_proxy=None,
):
"""
Args:
hs (synapse.server.HomeServer)
treq_args (dict): Extra keyword arguments to be given to treq.request.
ip_blacklist (netaddr.IPSet): The IP addresses that are blacklisted that
we may not request.
ip_whitelist (netaddr.IPSet): The whitelisted IP addresses, that we can
request if it were otherwise caught in a blacklist.
http_proxy (bytes): proxy server to use for http connections. host[:port]
https_proxy (bytes): proxy server to use for https connections. host[:port]
"""
self.hs = hs
self._ip_whitelist = ip_whitelist
self._ip_blacklist = ip_blacklist
self._extra_treq_args = treq_args
self.user_agent = hs.version_string
self.clock = hs.get_clock()
if hs.config.user_agent_suffix:
self.user_agent = "%s %s" % (self.user_agent, hs.config.user_agent_suffix)
# We use this for our body producers to ensure that they use the correct
# reactor.
self._cooperator = Cooperator(scheduler=_make_scheduler(hs.get_reactor()))
self.user_agent = self.user_agent.encode("ascii")
if self._ip_blacklist:
real_reactor = hs.get_reactor()
# If we have an IP blacklist, we need to use a DNS resolver which
# filters out blacklisted IP addresses, to prevent DNS rebinding.
nameResolver = IPBlacklistingResolver(
real_reactor, self._ip_whitelist, self._ip_blacklist
)
@implementer(IReactorPluggableNameResolver)
class Reactor:
def __getattr__(_self, attr):
if attr == "nameResolver":
return nameResolver
else:
return getattr(real_reactor, attr)
self.reactor = Reactor()
else:
self.reactor = hs.get_reactor()
# the pusher makes lots of concurrent SSL connections to sygnal, and
# tends to do so in batches, so we need to allow the pool to keep
# lots of idle connections around.
pool = HTTPConnectionPool(self.reactor)
# XXX: The justification for using the cache factor here is that larger instances
# will need both more cache and more connections.
# Still, this should probably be a separate dial
pool.maxPersistentPerHost = max((100 * hs.config.caches.global_factor, 5))
pool.cachedConnectionTimeout = 2 * 60
self.agent = ProxyAgent(
self.reactor,
connectTimeout=15,
contextFactory=self.hs.get_http_client_context_factory(),
pool=pool,
http_proxy=http_proxy,
https_proxy=https_proxy,
)
if self._ip_blacklist:
# If we have an IP blacklist, we then install the blacklisting Agent
# which prevents direct access to IP addresses, that are not caught
# by the DNS resolution.
self.agent = BlacklistingAgentWrapper(
self.agent,
self.reactor,
ip_whitelist=self._ip_whitelist,
ip_blacklist=self._ip_blacklist,
)
async def request(
self,
method: str,
uri: str,
data: Optional[bytes] = None,
headers: Optional[Headers] = None,
) -> IResponse:
"""
Args:
method: HTTP method to use.
uri: URI to query.
data: Data to send in the request body, if applicable.
headers: Request headers.
Returns:
Response object, once the headers have been read.
Raises:
RequestTimedOutError if the request times out before the headers are read
"""
outgoing_requests_counter.labels(method).inc()
# log request but strip `access_token` (AS requests for example include this)
logger.debug("Sending request %s %s", method, redact_uri(uri))
with start_active_span(
"outgoing-client-request",
tags={
tags.SPAN_KIND: tags.SPAN_KIND_RPC_CLIENT,
tags.HTTP_METHOD: method,
tags.HTTP_URL: uri,
},
finish_on_close=True,
):
try:
body_producer = None
if data is not None:
body_producer = QuieterFileBodyProducer(
BytesIO(data), cooperator=self._cooperator,
)
request_deferred = treq.request(
method,
uri,
agent=self.agent,
data=body_producer,
headers=headers,
**self._extra_treq_args
) # type: defer.Deferred
# we use our own timeout mechanism rather than treq's as a workaround
# for https://twistedmatrix.com/trac/ticket/9534.
request_deferred = timeout_deferred(
request_deferred, 60, self.hs.get_reactor(),
)
# turn timeouts into RequestTimedOutErrors
request_deferred.addErrback(_timeout_to_request_timed_out_error)
response = await make_deferred_yieldable(request_deferred)
incoming_responses_counter.labels(method, response.code).inc()
logger.info(
"Received response to %s %s: %s",
method,
redact_uri(uri),
response.code,
)
return response
except Exception as e:
incoming_responses_counter.labels(method, "ERR").inc()
logger.info(
"Error sending request to %s %s: %s %s",
method,
redact_uri(uri),
type(e).__name__,
e.args[0],
)
set_tag(tags.ERROR, True)
set_tag("error_reason", e.args[0])
raise
async def post_urlencoded_get_json(
self,
uri: str,
args: Mapping[str, Union[str, List[str]]] = {},
headers: Optional[RawHeaders] = None,
) -> Any:
"""
Args:
uri: uri to query
args: parameters to be url-encoded in the body
headers: a map from header name to a list of values for that header
Returns:
parsed json
Raises:
RequestTimedOutError: if there is a timeout before the response headers
are received. Note there is currently no timeout on reading the response
body.
HttpResponseException: On a non-2xx HTTP response.
ValueError: if the response was not JSON
"""
# TODO: Do we ever want to log message contents?
logger.debug("post_urlencoded_get_json args: %s", args)
query_bytes = urllib.parse.urlencode(encode_urlencode_args(args), True).encode(
"utf8"
)
actual_headers = {
b"Content-Type": [b"application/x-www-form-urlencoded"],
b"User-Agent": [self.user_agent],
b"Accept": [b"application/json"],
}
if headers:
actual_headers.update(headers)
response = await self.request(
"POST", uri, headers=Headers(actual_headers), data=query_bytes
)
body = await make_deferred_yieldable(readBody(response))
if 200 <= response.code < 300:
return json_decoder.decode(body.decode("utf-8"))
else:
raise HttpResponseException(
response.code, response.phrase.decode("ascii", errors="replace"), body
)
async def post_json_get_json(
self, uri: str, post_json: Any, headers: Optional[RawHeaders] = None
) -> Any:
"""
Args:
uri: URI to query.
post_json: request body, to be encoded as json
headers: a map from header name to a list of values for that header
Returns:
parsed json
Raises:
RequestTimedOutError: if there is a timeout before the response headers
are received. Note there is currently no timeout on reading the response
body.
HttpResponseException: On a non-2xx HTTP response.
ValueError: if the response was not JSON
"""
json_str = encode_canonical_json(post_json)
logger.debug("HTTP POST %s -> %s", json_str, uri)
actual_headers = {
b"Content-Type": [b"application/json"],
b"User-Agent": [self.user_agent],
b"Accept": [b"application/json"],
}
if headers:
actual_headers.update(headers)
response = await self.request(
"POST", uri, headers=Headers(actual_headers), data=json_str
)
body = await make_deferred_yieldable(readBody(response))
if 200 <= response.code < 300:
return json_decoder.decode(body.decode("utf-8"))
else:
raise HttpResponseException(
response.code, response.phrase.decode("ascii", errors="replace"), body
)
async def get_json(
self, uri: str, args: QueryParams = {}, headers: Optional[RawHeaders] = None,
) -> Any:
"""Gets some json from the given URI.
Args:
uri: The URI to request, not including query parameters
args: A dictionary used to create query string
headers: a map from header name to a list of values for that header
Returns:
Succeeds when we get a 2xx HTTP response, with the HTTP body as JSON.
Raises:
RequestTimedOutError: if there is a timeout before the response headers
are received. Note there is currently no timeout on reading the response
body.
HttpResponseException On a non-2xx HTTP response.
ValueError: if the response was not JSON
"""
actual_headers = {b"Accept": [b"application/json"]}
if headers:
actual_headers.update(headers)
body = await self.get_raw(uri, args, headers=headers)
return json_decoder.decode(body.decode("utf-8"))
async def put_json(
self,
uri: str,
json_body: Any,
args: QueryParams = {},
headers: RawHeaders = None,
) -> Any:
"""Puts some json to the given URI.
Args:
uri: The URI to request, not including query parameters
json_body: The JSON to put in the HTTP body,
args: A dictionary used to create query strings
headers: a map from header name to a list of values for that header
Returns:
Succeeds when we get a 2xx HTTP response, with the HTTP body as JSON.
Raises:
RequestTimedOutError: if there is a timeout before the response headers
are received. Note there is currently no timeout on reading the response
body.
HttpResponseException On a non-2xx HTTP response.
ValueError: if the response was not JSON
"""
if len(args):
query_bytes = urllib.parse.urlencode(args, True)
uri = "%s?%s" % (uri, query_bytes)
json_str = encode_canonical_json(json_body)
actual_headers = {
b"Content-Type": [b"application/json"],
b"User-Agent": [self.user_agent],
b"Accept": [b"application/json"],
}
if headers:
actual_headers.update(headers)
response = await self.request(
"PUT", uri, headers=Headers(actual_headers), data=json_str
)
body = await make_deferred_yieldable(readBody(response))
if 200 <= response.code < 300:
return json_decoder.decode(body.decode("utf-8"))
else:
raise HttpResponseException(
response.code, response.phrase.decode("ascii", errors="replace"), body
)
async def get_raw(
self, uri: str, args: QueryParams = {}, headers: Optional[RawHeaders] = None
) -> bytes:
"""Gets raw text from the given URI.
Args:
uri: The URI to request, not including query parameters
args: A dictionary used to create query strings
headers: a map from header name to a list of values for that header
Returns:
Succeeds when we get a 2xx HTTP response, with the
HTTP body as bytes.
Raises:
RequestTimedOutError: if there is a timeout before the response headers
are received. Note there is currently no timeout on reading the response
body.
HttpResponseException on a non-2xx HTTP response.
"""
if len(args):
query_bytes = urllib.parse.urlencode(args, True)
uri = "%s?%s" % (uri, query_bytes)
actual_headers = {b"User-Agent": [self.user_agent]}
if headers:
actual_headers.update(headers)
response = await self.request("GET", uri, headers=Headers(actual_headers))
body = await make_deferred_yieldable(readBody(response))
if 200 <= response.code < 300:
return body
else:
raise HttpResponseException(
response.code, response.phrase.decode("ascii", errors="replace"), body
)
# XXX: FIXME: This is horribly copy-pasted from matrixfederationclient.
# The two should be factored out.
async def get_file(
self,
url: str,
output_stream: BinaryIO,
max_size: Optional[int] = None,
headers: Optional[RawHeaders] = None,
) -> Tuple[int, Dict[bytes, List[bytes]], str, int]:
"""GETs a file from a given URL
Args:
url: The URL to GET
output_stream: File to write the response body to.
headers: A map from header name to a list of values for that header
Returns:
A tuple of the file length, dict of the response
headers, absolute URI of the response and HTTP response code.
Raises:
RequestTimedOutError: if there is a timeout before the response headers
are received. Note there is currently no timeout on reading the response
body.
SynapseError: if the response is not a 2xx, the remote file is too large, or
another exception happens during the download.
"""
actual_headers = {b"User-Agent": [self.user_agent]}
if headers:
actual_headers.update(headers)
response = await self.request("GET", url, headers=Headers(actual_headers))
resp_headers = dict(response.headers.getAllRawHeaders())
if (
b"Content-Length" in resp_headers
and int(resp_headers[b"Content-Length"][0]) > max_size
):
logger.warning("Requested URL is too large > %r bytes" % (self.max_size,))
raise SynapseError(
502,
"Requested file is too large > %r bytes" % (self.max_size,),
Codes.TOO_LARGE,
)
if response.code > 299:
logger.warning("Got %d when downloading %s" % (response.code, url))
raise SynapseError(502, "Got error %d" % (response.code,), Codes.UNKNOWN)
# TODO: if our Content-Type is HTML or something, just read the first
# N bytes into RAM rather than saving it all to disk only to read it
# straight back in again
try:
length = await make_deferred_yieldable(
_readBodyToFile(response, output_stream, max_size)
)
except SynapseError:
# This can happen e.g. because the body is too large.
raise
except Exception as e:
raise SynapseError(502, ("Failed to download remote body: %s" % e)) from e
return (
length,
resp_headers,
response.request.absoluteURI.decode("ascii"),
response.code,
)
def _timeout_to_request_timed_out_error(f: Failure):
if f.check(twisted_error.TimeoutError, twisted_error.ConnectingCancelledError):
# The TCP connection has its own timeout (set by the 'connectTimeout' param
# on the Agent), which raises twisted_error.TimeoutError exception.
raise RequestTimedOutError("Timeout connecting to remote server")
elif f.check(defer.TimeoutError, ResponseNeverReceived):
# this one means that we hit our overall timeout on the request
raise RequestTimedOutError("Timeout waiting for response from remote server")
return f
# XXX: FIXME: This is horribly copy-pasted from matrixfederationclient.
# The two should be factored out.
class _ReadBodyToFileProtocol(protocol.Protocol):
def __init__(self, stream, deferred, max_size):
self.stream = stream
self.deferred = deferred
self.length = 0
self.max_size = max_size
def dataReceived(self, data):
self.stream.write(data)
self.length += len(data)
if self.max_size is not None and self.length >= self.max_size:
self.deferred.errback(
SynapseError(
502,
"Requested file is too large > %r bytes" % (self.max_size,),
Codes.TOO_LARGE,
)
)
self.deferred = defer.Deferred()
self.transport.loseConnection()
def connectionLost(self, reason):
if reason.check(ResponseDone):
self.deferred.callback(self.length)
elif reason.check(PotentialDataLoss):
# stolen from https://github.com/twisted/treq/pull/49/files
# http://twistedmatrix.com/trac/ticket/4840
self.deferred.callback(self.length)
else:
self.deferred.errback(reason)
# XXX: FIXME: This is horribly copy-pasted from matrixfederationclient.
# The two should be factored out.
def _readBodyToFile(response, stream, max_size):
d = defer.Deferred()
response.deliverBody(_ReadBodyToFileProtocol(stream, d, max_size))
return d
def encode_urlencode_args(args):
return {k: encode_urlencode_arg(v) for k, v in args.items()}
def encode_urlencode_arg(arg):
if isinstance(arg, str):
return arg.encode("utf-8")
elif isinstance(arg, list):
return [encode_urlencode_arg(i) for i in arg]
else:
return arg
def _print_ex(e):
if hasattr(e, "reasons") and e.reasons:
for ex in e.reasons:
_print_ex(ex)
else:
logger.exception(e)
class InsecureInterceptableContextFactory(ssl.ContextFactory):
"""
Factory for PyOpenSSL SSL contexts which accepts any certificate for any domain.
Do not use this since it allows an attacker to intercept your communications.
"""
def __init__(self):
self._context = SSL.Context(SSL.SSLv23_METHOD)
self._context.set_verify(VERIFY_NONE, lambda *_: None)
def getContext(self, hostname=None, port=None):
return self._context
def creatorForNetloc(self, hostname, port):
return self
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