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# -*- coding: utf-8 -*-
# Copyright 2019 The Matrix.org Foundation C.I.C.
#
# 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
from zope.interface import implementer
from twisted.internet import defer, protocol
from twisted.internet.error import ConnectError
from twisted.internet.interfaces import IStreamClientEndpoint
from twisted.internet.protocol import connectionDone
from twisted.web import http
logger = logging.getLogger(__name__)
class ProxyConnectError(ConnectError):
pass
@implementer(IStreamClientEndpoint)
class HTTPConnectProxyEndpoint:
"""An Endpoint implementation which will send a CONNECT request to an http proxy
Wraps an existing HostnameEndpoint for the proxy.
When we get the connect() request from the connection pool (via the TLS wrapper),
we'll first connect to the proxy endpoint with a ProtocolFactory which will make the
CONNECT request. Once that completes, we invoke the protocolFactory which was passed
in.
Args:
reactor: the Twisted reactor to use for the connection
proxy_endpoint (IStreamClientEndpoint): the endpoint to use to connect to the
proxy
host (bytes): hostname that we want to CONNECT to
port (int): port that we want to connect to
"""
def __init__(self, reactor, proxy_endpoint, host, port):
self._reactor = reactor
self._proxy_endpoint = proxy_endpoint
self._host = host
self._port = port
def __repr__(self):
return "<HTTPConnectProxyEndpoint %s>" % (self._proxy_endpoint,)
def connect(self, protocolFactory):
f = HTTPProxiedClientFactory(self._host, self._port, protocolFactory)
d = self._proxy_endpoint.connect(f)
# once the tcp socket connects successfully, we need to wait for the
# CONNECT to complete.
d.addCallback(lambda conn: f.on_connection)
return d
class HTTPProxiedClientFactory(protocol.ClientFactory):
"""ClientFactory wrapper that triggers an HTTP proxy CONNECT on connect.
Once the CONNECT completes, invokes the original ClientFactory to build the
HTTP Protocol object and run the rest of the connection.
Args:
dst_host (bytes): hostname that we want to CONNECT to
dst_port (int): port that we want to connect to
wrapped_factory (protocol.ClientFactory): The original Factory
"""
def __init__(self, dst_host, dst_port, wrapped_factory):
self.dst_host = dst_host
self.dst_port = dst_port
self.wrapped_factory = wrapped_factory
self.on_connection = defer.Deferred()
def startedConnecting(self, connector):
return self.wrapped_factory.startedConnecting(connector)
def buildProtocol(self, addr):
wrapped_protocol = self.wrapped_factory.buildProtocol(addr)
return HTTPConnectProtocol(
self.dst_host, self.dst_port, wrapped_protocol, self.on_connection
)
def clientConnectionFailed(self, connector, reason):
logger.debug("Connection to proxy failed: %s", reason)
if not self.on_connection.called:
self.on_connection.errback(reason)
return self.wrapped_factory.clientConnectionFailed(connector, reason)
def clientConnectionLost(self, connector, reason):
logger.debug("Connection to proxy lost: %s", reason)
if not self.on_connection.called:
self.on_connection.errback(reason)
return self.wrapped_factory.clientConnectionLost(connector, reason)
class HTTPConnectProtocol(protocol.Protocol):
"""Protocol that wraps an existing Protocol to do a CONNECT handshake at connect
Args:
host (bytes): The original HTTP(s) hostname or IPv4 or IPv6 address literal
to put in the CONNECT request
port (int): The original HTTP(s) port to put in the CONNECT request
wrapped_protocol (interfaces.IProtocol): the original protocol (probably
HTTPChannel or TLSMemoryBIOProtocol, but could be anything really)
connected_deferred (Deferred): a Deferred which will be callbacked with
wrapped_protocol when the CONNECT completes
"""
def __init__(self, host, port, wrapped_protocol, connected_deferred):
self.host = host
self.port = port
self.wrapped_protocol = wrapped_protocol
self.connected_deferred = connected_deferred
self.http_setup_client = HTTPConnectSetupClient(self.host, self.port)
self.http_setup_client.on_connected.addCallback(self.proxyConnected)
def connectionMade(self):
self.http_setup_client.makeConnection(self.transport)
def connectionLost(self, reason=connectionDone):
if self.wrapped_protocol.connected:
self.wrapped_protocol.connectionLost(reason)
self.http_setup_client.connectionLost(reason)
if not self.connected_deferred.called:
self.connected_deferred.errback(reason)
def proxyConnected(self, _):
self.wrapped_protocol.makeConnection(self.transport)
self.connected_deferred.callback(self.wrapped_protocol)
# Get any pending data from the http buf and forward it to the original protocol
buf = self.http_setup_client.clearLineBuffer()
if buf:
self.wrapped_protocol.dataReceived(buf)
def dataReceived(self, data):
# if we've set up the HTTP protocol, we can send the data there
if self.wrapped_protocol.connected:
return self.wrapped_protocol.dataReceived(data)
# otherwise, we must still be setting up the connection: send the data to the
# setup client
return self.http_setup_client.dataReceived(data)
class HTTPConnectSetupClient(http.HTTPClient):
"""HTTPClient protocol to send a CONNECT message for proxies and read the response.
Args:
host (bytes): The hostname to send in the CONNECT message
port (int): The port to send in the CONNECT message
"""
def __init__(self, host, port):
self.host = host
self.port = port
self.on_connected = defer.Deferred()
def connectionMade(self):
logger.debug("Connected to proxy, sending CONNECT")
self.sendCommand(b"CONNECT", b"%s:%d" % (self.host, self.port))
self.endHeaders()
def handleStatus(self, version, status, message):
logger.debug("Got Status: %s %s %s", status, message, version)
if status != b"200":
raise ProxyConnectError("Unexpected status on CONNECT: %s" % status)
def handleEndHeaders(self):
logger.debug("End Headers")
self.on_connected.callback(None)
def handleResponse(self, body):
pass
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