271 lines
9.2 KiB
Python
271 lines
9.2 KiB
Python
# Copyright 2019 The Matrix.org Foundation C.I.C.
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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 base64
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import logging
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from typing import Optional
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import attr
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from zope.interface import implementer
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from twisted.internet import defer, protocol
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from twisted.internet.error import ConnectError
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from twisted.internet.interfaces import IReactorCore, IStreamClientEndpoint
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from twisted.internet.protocol import ClientFactory, Protocol, connectionDone
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from twisted.web import http
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logger = logging.getLogger(__name__)
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class ProxyConnectError(ConnectError):
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pass
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@attr.s
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class ProxyCredentials:
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username_password = attr.ib(type=bytes)
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def as_proxy_authorization_value(self) -> bytes:
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"""
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Return the value for a Proxy-Authorization header (i.e. 'Basic abdef==').
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Returns:
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A transformation of the authentication string the encoded value for
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a Proxy-Authorization header.
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"""
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# Encode as base64 and prepend the authorization type
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return b"Basic " + base64.encodebytes(self.username_password)
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@implementer(IStreamClientEndpoint)
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class HTTPConnectProxyEndpoint:
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"""An Endpoint implementation which will send a CONNECT request to an http proxy
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Wraps an existing HostnameEndpoint for the proxy.
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When we get the connect() request from the connection pool (via the TLS wrapper),
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we'll first connect to the proxy endpoint with a ProtocolFactory which will make the
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CONNECT request. Once that completes, we invoke the protocolFactory which was passed
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in.
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Args:
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reactor: the Twisted reactor to use for the connection
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proxy_endpoint: the endpoint to use to connect to the proxy
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host: hostname that we want to CONNECT to
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port: port that we want to connect to
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proxy_creds: credentials to authenticate at proxy
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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_endpoint: IStreamClientEndpoint,
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host: bytes,
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port: int,
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proxy_creds: Optional[ProxyCredentials],
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):
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self._reactor = reactor
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self._proxy_endpoint = proxy_endpoint
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self._host = host
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self._port = port
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self._proxy_creds = proxy_creds
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def __repr__(self):
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return "<HTTPConnectProxyEndpoint %s>" % (self._proxy_endpoint,)
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# Mypy encounters a false positive here: it complains that ClientFactory
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# is incompatible with IProtocolFactory. But ClientFactory inherits from
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# Factory, which implements IProtocolFactory. So I think this is a bug
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# in mypy-zope.
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def connect(self, protocolFactory: ClientFactory): # type: ignore[override]
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f = HTTPProxiedClientFactory(
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self._host, self._port, protocolFactory, self._proxy_creds
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)
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d = self._proxy_endpoint.connect(f)
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# once the tcp socket connects successfully, we need to wait for the
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# CONNECT to complete.
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d.addCallback(lambda conn: f.on_connection)
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return d
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class HTTPProxiedClientFactory(protocol.ClientFactory):
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"""ClientFactory wrapper that triggers an HTTP proxy CONNECT on connect.
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Once the CONNECT completes, invokes the original ClientFactory to build the
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HTTP Protocol object and run the rest of the connection.
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Args:
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dst_host: hostname that we want to CONNECT to
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dst_port: port that we want to connect to
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wrapped_factory: The original Factory
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proxy_creds: credentials to authenticate at proxy
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"""
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def __init__(
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self,
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dst_host: bytes,
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dst_port: int,
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wrapped_factory: ClientFactory,
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proxy_creds: Optional[ProxyCredentials],
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):
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self.dst_host = dst_host
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self.dst_port = dst_port
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self.wrapped_factory = wrapped_factory
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self.proxy_creds = proxy_creds
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self.on_connection: "defer.Deferred[None]" = defer.Deferred()
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def startedConnecting(self, connector):
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return self.wrapped_factory.startedConnecting(connector)
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def buildProtocol(self, addr):
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wrapped_protocol = self.wrapped_factory.buildProtocol(addr)
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if wrapped_protocol is None:
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raise TypeError("buildProtocol produced None instead of a Protocol")
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return HTTPConnectProtocol(
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self.dst_host,
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self.dst_port,
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wrapped_protocol,
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self.on_connection,
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self.proxy_creds,
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)
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def clientConnectionFailed(self, connector, reason):
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logger.debug("Connection to proxy failed: %s", reason)
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if not self.on_connection.called:
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self.on_connection.errback(reason)
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return self.wrapped_factory.clientConnectionFailed(connector, reason)
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def clientConnectionLost(self, connector, reason):
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logger.debug("Connection to proxy lost: %s", reason)
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if not self.on_connection.called:
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self.on_connection.errback(reason)
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return self.wrapped_factory.clientConnectionLost(connector, reason)
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class HTTPConnectProtocol(protocol.Protocol):
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"""Protocol that wraps an existing Protocol to do a CONNECT handshake at connect
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Args:
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host: The original HTTP(s) hostname or IPv4 or IPv6 address literal
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to put in the CONNECT request
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port: The original HTTP(s) port to put in the CONNECT request
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wrapped_protocol: the original protocol (probably HTTPChannel or
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TLSMemoryBIOProtocol, but could be anything really)
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connected_deferred: a Deferred which will be callbacked with
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wrapped_protocol when the CONNECT completes
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proxy_creds: credentials to authenticate at proxy
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"""
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def __init__(
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self,
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host: bytes,
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port: int,
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wrapped_protocol: Protocol,
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connected_deferred: defer.Deferred,
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proxy_creds: Optional[ProxyCredentials],
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):
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self.host = host
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self.port = port
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self.wrapped_protocol = wrapped_protocol
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self.connected_deferred = connected_deferred
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self.proxy_creds = proxy_creds
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self.http_setup_client = HTTPConnectSetupClient(
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self.host, self.port, self.proxy_creds
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)
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self.http_setup_client.on_connected.addCallback(self.proxyConnected)
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def connectionMade(self):
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self.http_setup_client.makeConnection(self.transport)
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def connectionLost(self, reason=connectionDone):
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if self.wrapped_protocol.connected:
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self.wrapped_protocol.connectionLost(reason)
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self.http_setup_client.connectionLost(reason)
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if not self.connected_deferred.called:
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self.connected_deferred.errback(reason)
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def proxyConnected(self, _):
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self.wrapped_protocol.makeConnection(self.transport)
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self.connected_deferred.callback(self.wrapped_protocol)
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# Get any pending data from the http buf and forward it to the original protocol
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buf = self.http_setup_client.clearLineBuffer()
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if buf:
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self.wrapped_protocol.dataReceived(buf)
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def dataReceived(self, data: bytes):
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# if we've set up the HTTP protocol, we can send the data there
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if self.wrapped_protocol.connected:
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return self.wrapped_protocol.dataReceived(data)
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# otherwise, we must still be setting up the connection: send the data to the
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# setup client
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return self.http_setup_client.dataReceived(data)
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class HTTPConnectSetupClient(http.HTTPClient):
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"""HTTPClient protocol to send a CONNECT message for proxies and read the response.
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Args:
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host: The hostname to send in the CONNECT message
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port: The port to send in the CONNECT message
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proxy_creds: credentials to authenticate at proxy
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"""
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def __init__(
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self,
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host: bytes,
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port: int,
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proxy_creds: Optional[ProxyCredentials],
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):
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self.host = host
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self.port = port
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self.proxy_creds = proxy_creds
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self.on_connected: "defer.Deferred[None]" = defer.Deferred()
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def connectionMade(self):
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logger.debug("Connected to proxy, sending CONNECT")
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self.sendCommand(b"CONNECT", b"%s:%d" % (self.host, self.port))
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# Determine whether we need to set Proxy-Authorization headers
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if self.proxy_creds:
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# Set a Proxy-Authorization header
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self.sendHeader(
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b"Proxy-Authorization",
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self.proxy_creds.as_proxy_authorization_value(),
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)
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self.endHeaders()
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def handleStatus(self, version: bytes, status: bytes, message: bytes):
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logger.debug("Got Status: %s %s %s", status, message, version)
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if status != b"200":
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raise ProxyConnectError(f"Unexpected status on CONNECT: {status!s}")
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def handleEndHeaders(self):
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logger.debug("End Headers")
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self.on_connected.callback(None)
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def handleResponse(self, body):
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pass
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