435 lines
16 KiB
Python
435 lines
16 KiB
Python
# Copyright 2019 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 logging
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import urllib.parse
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from typing import Any, Generator, List, Optional
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from urllib.request import ( # type: ignore[attr-defined]
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getproxies_environment,
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proxy_bypass_environment,
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)
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from netaddr import AddrFormatError, IPAddress, IPSet
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from zope.interface import implementer
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from twisted.internet import defer
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from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
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from twisted.internet.interfaces import (
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IProtocol,
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IProtocolFactory,
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IReactorCore,
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IStreamClientEndpoint,
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)
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from twisted.web.client import URI, Agent, HTTPConnectionPool
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from twisted.web.http_headers import Headers
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from twisted.web.iweb import IAgent, IAgentEndpointFactory, IBodyProducer, IResponse
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from synapse.crypto.context_factory import FederationPolicyForHTTPS
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from synapse.http import proxyagent
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from synapse.http.client import BlocklistingAgentWrapper, BlocklistingReactorWrapper
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from synapse.http.connectproxyclient import HTTPConnectProxyEndpoint
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from synapse.http.federation.srv_resolver import Server, SrvResolver
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from synapse.http.federation.well_known_resolver import WellKnownResolver
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from synapse.http.proxyagent import ProxyAgent
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from synapse.logging.context import make_deferred_yieldable, run_in_background
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from synapse.types import ISynapseReactor
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from synapse.util import Clock
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logger = logging.getLogger(__name__)
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@implementer(IAgent)
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class MatrixFederationAgent:
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"""An Agent-like thing which provides a `request` method which correctly
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handles resolving matrix server names when using `matrix-federation://`. Handles
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standard https URIs as normal. The `matrix-federation://` scheme is internal to
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Synapse and we purposely want to avoid colliding with the `matrix://` URL scheme
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which is now specced.
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Doesn't implement any retries. (Those are done in MatrixFederationHttpClient.)
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Args:
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reactor: twisted reactor to use for underlying requests
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tls_client_options_factory:
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factory to use for fetching client tls options, or none to disable TLS.
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user_agent:
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The user agent header to use for federation requests.
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ip_allowlist: Allowed IP addresses.
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ip_blocklist: Disallowed IP addresses.
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proxy_reactor: twisted reactor to use for connections to the proxy server
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reactor might have some blocking applied (i.e. for DNS queries),
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but we need unblocked access to the proxy.
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_srv_resolver:
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SrvResolver implementation to use for looking up SRV records. None
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to use a default implementation.
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_well_known_resolver:
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WellKnownResolver to use to perform well-known lookups. None to use a
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default implementation.
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"""
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def __init__(
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self,
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reactor: ISynapseReactor,
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tls_client_options_factory: Optional[FederationPolicyForHTTPS],
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user_agent: bytes,
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ip_allowlist: Optional[IPSet],
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ip_blocklist: IPSet,
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_srv_resolver: Optional[SrvResolver] = None,
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_well_known_resolver: Optional[WellKnownResolver] = None,
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):
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# proxy_reactor is not blocklisting reactor
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proxy_reactor = reactor
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# We need to use a DNS resolver which filters out blocked IP
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# addresses, to prevent DNS rebinding.
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reactor = BlocklistingReactorWrapper(reactor, ip_allowlist, ip_blocklist)
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self._clock = Clock(reactor)
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self._pool = HTTPConnectionPool(reactor)
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self._pool.retryAutomatically = False
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self._pool.maxPersistentPerHost = 5
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self._pool.cachedConnectionTimeout = 2 * 60
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self._agent = Agent.usingEndpointFactory(
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reactor,
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MatrixHostnameEndpointFactory(
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reactor,
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proxy_reactor,
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tls_client_options_factory,
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_srv_resolver,
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),
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pool=self._pool,
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)
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self.user_agent = user_agent
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if _well_known_resolver is None:
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_well_known_resolver = WellKnownResolver(
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reactor,
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agent=BlocklistingAgentWrapper(
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ProxyAgent(
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reactor,
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proxy_reactor,
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pool=self._pool,
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contextFactory=tls_client_options_factory,
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use_proxy=True,
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),
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ip_blocklist=ip_blocklist,
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),
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user_agent=self.user_agent,
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)
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self._well_known_resolver = _well_known_resolver
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@defer.inlineCallbacks
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def request(
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self,
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method: bytes,
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uri: bytes,
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headers: Optional[Headers] = None,
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bodyProducer: Optional[IBodyProducer] = None,
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) -> Generator[defer.Deferred, Any, IResponse]:
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"""
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Args:
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method: HTTP method: GET/POST/etc
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uri: Absolute URI to be retrieved
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headers:
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HTTP headers to send with the request, or None to send no extra headers.
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bodyProducer:
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An object which can generate bytes to make up the
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body of this request (for example, the properly encoded contents of
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a file for a file upload). Or None if the request is to have
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no body.
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Returns:
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A deferred which fires when the header of the response has been received
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(regardless of the response status code). Fails if there is any problem
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which prevents that response from being received (including problems that
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prevent the request from being sent).
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"""
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# We use urlparse as that will set `port` to None if there is no
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# explicit port.
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parsed_uri = urllib.parse.urlparse(uri)
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# There must be a valid hostname.
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assert parsed_uri.hostname
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# If this is a matrix-federation:// URI check if the server has delegated matrix
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# traffic using well-known delegation.
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#
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# We have to do this here and not in the endpoint as we need to rewrite
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# the host header with the delegated server name.
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delegated_server = None
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if (
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parsed_uri.scheme == b"matrix-federation"
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and not _is_ip_literal(parsed_uri.hostname)
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and not parsed_uri.port
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):
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well_known_result = yield defer.ensureDeferred(
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self._well_known_resolver.get_well_known(parsed_uri.hostname)
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)
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delegated_server = well_known_result.delegated_server
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if delegated_server:
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# Ok, the server has delegated matrix traffic to somewhere else, so
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# lets rewrite the URL to replace the server with the delegated
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# server name.
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uri = urllib.parse.urlunparse(
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(
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parsed_uri.scheme,
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delegated_server,
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parsed_uri.path,
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parsed_uri.params,
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parsed_uri.query,
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parsed_uri.fragment,
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)
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)
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parsed_uri = urllib.parse.urlparse(uri)
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# We need to make sure the host header is set to the netloc of the
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# server and that a user-agent is provided.
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if headers is None:
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request_headers = Headers()
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else:
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request_headers = headers.copy()
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if not request_headers.hasHeader(b"host"):
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request_headers.addRawHeader(b"host", parsed_uri.netloc)
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if not request_headers.hasHeader(b"user-agent"):
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request_headers.addRawHeader(b"user-agent", self.user_agent)
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res = yield make_deferred_yieldable(
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self._agent.request(method, uri, request_headers, bodyProducer)
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)
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return res
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@implementer(IAgentEndpointFactory)
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class MatrixHostnameEndpointFactory:
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"""Factory for MatrixHostnameEndpoint for parsing to an Agent."""
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def __init__(
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self,
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reactor: IReactorCore,
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proxy_reactor: IReactorCore,
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tls_client_options_factory: Optional[FederationPolicyForHTTPS],
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srv_resolver: Optional[SrvResolver],
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):
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self._reactor = reactor
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self._proxy_reactor = proxy_reactor
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self._tls_client_options_factory = tls_client_options_factory
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if srv_resolver is None:
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srv_resolver = SrvResolver()
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self._srv_resolver = srv_resolver
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def endpointForURI(self, parsed_uri: URI) -> "MatrixHostnameEndpoint":
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return MatrixHostnameEndpoint(
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self._reactor,
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self._proxy_reactor,
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self._tls_client_options_factory,
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self._srv_resolver,
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parsed_uri,
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)
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@implementer(IStreamClientEndpoint)
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class MatrixHostnameEndpoint:
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"""An endpoint that resolves matrix-federation:// URLs using Matrix server name
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resolution (i.e. via SRV). Does not check for well-known delegation.
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Args:
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reactor: twisted reactor to use for underlying requests
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proxy_reactor: twisted reactor to use for connections to the proxy server.
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'reactor' might have some blocking applied (i.e. for DNS queries),
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but we need unblocked access to the proxy.
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tls_client_options_factory:
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factory to use for fetching client tls options, or none to disable TLS.
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srv_resolver: The SRV resolver to use
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parsed_uri: The parsed URI that we're wanting to connect to.
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Raises:
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ValueError if the environment variables contain an invalid proxy specification.
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RuntimeError if no tls_options_factory is given for a https connection
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"""
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def __init__(
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self,
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reactor: IReactorCore,
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proxy_reactor: IReactorCore,
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tls_client_options_factory: Optional[FederationPolicyForHTTPS],
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srv_resolver: SrvResolver,
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parsed_uri: URI,
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):
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self._reactor = reactor
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self._parsed_uri = parsed_uri
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# http_proxy is not needed because federation is always over TLS
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proxies = getproxies_environment()
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https_proxy = proxies["https"].encode() if "https" in proxies else None
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self.no_proxy = proxies["no"] if "no" in proxies else None
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# endpoint and credentials to use to connect to the outbound https proxy, if any.
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(
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self._https_proxy_endpoint,
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self._https_proxy_creds,
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) = proxyagent.http_proxy_endpoint(
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https_proxy,
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proxy_reactor,
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tls_client_options_factory,
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)
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# set up the TLS connection params
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#
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# XXX disabling TLS is really only supported here for the benefit of the
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# unit tests. We should make the UTs cope with TLS rather than having to make
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# the code support the unit tests.
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if tls_client_options_factory is None:
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self._tls_options = None
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else:
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self._tls_options = tls_client_options_factory.get_options(
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self._parsed_uri.host
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)
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self._srv_resolver = srv_resolver
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def connect(
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self, protocol_factory: IProtocolFactory
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) -> "defer.Deferred[IProtocol]":
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"""Implements IStreamClientEndpoint interface"""
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return run_in_background(self._do_connect, protocol_factory)
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async def _do_connect(self, protocol_factory: IProtocolFactory) -> IProtocol:
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first_exception = None
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server_list = await self._resolve_server()
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for server in server_list:
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host = server.host
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port = server.port
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should_skip_proxy = False
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if self.no_proxy is not None:
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should_skip_proxy = proxy_bypass_environment(
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host.decode(),
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proxies={"no": self.no_proxy},
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)
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endpoint: IStreamClientEndpoint
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try:
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if self._https_proxy_endpoint and not should_skip_proxy:
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logger.debug(
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"Connecting to %s:%i via %s",
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host.decode("ascii"),
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port,
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self._https_proxy_endpoint,
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)
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endpoint = HTTPConnectProxyEndpoint(
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self._reactor,
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self._https_proxy_endpoint,
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host,
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port,
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proxy_creds=self._https_proxy_creds,
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)
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else:
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logger.debug("Connecting to %s:%i", host.decode("ascii"), port)
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# not using a proxy
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endpoint = HostnameEndpoint(self._reactor, host, port)
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if self._tls_options:
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endpoint = wrapClientTLS(self._tls_options, endpoint)
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result = await make_deferred_yieldable(
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endpoint.connect(protocol_factory)
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)
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return result
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except Exception as e:
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logger.info(
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"Failed to connect to %s:%i: %s", host.decode("ascii"), port, e
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)
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if not first_exception:
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first_exception = e
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# We return the first failure because that's probably the most interesting.
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if first_exception:
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raise first_exception
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# This shouldn't happen as we should always have at least one host/port
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# to try and if that doesn't work then we'll have an exception.
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raise Exception("Failed to resolve server %r" % (self._parsed_uri.netloc,))
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async def _resolve_server(self) -> List[Server]:
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"""Resolves the server name to a list of hosts and ports to attempt to
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connect to.
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"""
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if self._parsed_uri.scheme != b"matrix-federation":
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return [Server(host=self._parsed_uri.host, port=self._parsed_uri.port)]
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# Note: We don't do well-known lookup as that needs to have happened
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# before now, due to needing to rewrite the Host header of the HTTP
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# request.
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# We reparse the URI so that defaultPort is -1 rather than 80
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parsed_uri = urllib.parse.urlparse(self._parsed_uri.toBytes())
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host = parsed_uri.hostname
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port = parsed_uri.port
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# If there is an explicit port or the host is an IP address we bypass
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# SRV lookups and just use the given host/port.
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if port or _is_ip_literal(host):
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return [Server(host, port or 8448)]
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logger.debug("Looking up SRV record for %s", host.decode(errors="replace"))
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server_list = await self._srv_resolver.resolve_service(b"_matrix._tcp." + host)
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if server_list:
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logger.debug(
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"Got %s from SRV lookup for %s",
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", ".join(map(str, server_list)),
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host.decode(errors="replace"),
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)
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return server_list
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# No SRV records, so we fallback to host and 8448
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logger.debug("No SRV records for %s", host.decode(errors="replace"))
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return [Server(host, 8448)]
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def _is_ip_literal(host: bytes) -> bool:
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"""Test if the given host name is either an IPv4 or IPv6 literal.
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Args:
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host: The host name to check
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Returns:
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True if the hostname is an IP address literal.
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"""
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host_str = host.decode("ascii")
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try:
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IPAddress(host_str)
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return True
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except AddrFormatError:
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return False
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