# 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 base64 import logging from typing import Optional, Union import attr from zope.interface import implementer from twisted.internet import defer, protocol from twisted.internet.error import ConnectError from twisted.internet.interfaces import ( IAddress, IConnector, IProtocol, IReactorCore, IStreamClientEndpoint, ) from twisted.internet.protocol import ClientFactory, Protocol, connectionDone from twisted.python.failure import Failure from twisted.web import http logger = logging.getLogger(__name__) class ProxyConnectError(ConnectError): pass @attr.s(auto_attribs=True) class ProxyCredentials: username_password: bytes def as_proxy_authorization_value(self) -> bytes: """ Return the value for a Proxy-Authorization header (i.e. 'Basic abdef=='). Returns: A transformation of the authentication string the encoded value for a Proxy-Authorization header. """ # Encode as base64 and prepend the authorization type return b"Basic " + base64.encodebytes(self.username_password) @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: the endpoint to use to connect to the proxy host: hostname that we want to CONNECT to port: port that we want to connect to proxy_creds: credentials to authenticate at proxy """ def __init__( self, reactor: IReactorCore, proxy_endpoint: IStreamClientEndpoint, host: bytes, port: int, proxy_creds: Optional[ProxyCredentials], ): self._reactor = reactor self._proxy_endpoint = proxy_endpoint self._host = host self._port = port self._proxy_creds = proxy_creds def __repr__(self) -> str: return "<HTTPConnectProxyEndpoint %s>" % (self._proxy_endpoint,) # Mypy encounters a false positive here: it complains that ClientFactory # is incompatible with IProtocolFactory. But ClientFactory inherits from # Factory, which implements IProtocolFactory. So I think this is a bug # in mypy-zope. def connect(self, protocolFactory: ClientFactory) -> "defer.Deferred[IProtocol]": # type: ignore[override] f = HTTPProxiedClientFactory( self._host, self._port, protocolFactory, self._proxy_creds ) 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: hostname that we want to CONNECT to dst_port: port that we want to connect to wrapped_factory: The original Factory proxy_creds: credentials to authenticate at proxy """ def __init__( self, dst_host: bytes, dst_port: int, wrapped_factory: ClientFactory, proxy_creds: Optional[ProxyCredentials], ): self.dst_host = dst_host self.dst_port = dst_port self.wrapped_factory = wrapped_factory self.proxy_creds = proxy_creds self.on_connection: "defer.Deferred[None]" = defer.Deferred() def startedConnecting(self, connector: IConnector) -> None: return self.wrapped_factory.startedConnecting(connector) def buildProtocol(self, addr: IAddress) -> "HTTPConnectProtocol": wrapped_protocol = self.wrapped_factory.buildProtocol(addr) if wrapped_protocol is None: raise TypeError("buildProtocol produced None instead of a Protocol") return HTTPConnectProtocol( self.dst_host, self.dst_port, wrapped_protocol, self.on_connection, self.proxy_creds, ) def clientConnectionFailed(self, connector: IConnector, reason: Failure) -> None: 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: IConnector, reason: Failure) -> None: 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: The original HTTP(s) hostname or IPv4 or IPv6 address literal to put in the CONNECT request port: The original HTTP(s) port to put in the CONNECT request wrapped_protocol: the original protocol (probably HTTPChannel or TLSMemoryBIOProtocol, but could be anything really) connected_deferred: a Deferred which will be callbacked with wrapped_protocol when the CONNECT completes proxy_creds: credentials to authenticate at proxy """ def __init__( self, host: bytes, port: int, wrapped_protocol: Protocol, connected_deferred: defer.Deferred, proxy_creds: Optional[ProxyCredentials], ): self.host = host self.port = port self.wrapped_protocol = wrapped_protocol self.connected_deferred = connected_deferred self.proxy_creds = proxy_creds self.http_setup_client = HTTPConnectSetupClient( self.host, self.port, self.proxy_creds ) self.http_setup_client.on_connected.addCallback(self.proxyConnected) def connectionMade(self) -> None: self.http_setup_client.makeConnection(self.transport) def connectionLost(self, reason: Failure = connectionDone) -> None: 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, _: Union[None, "defer.Deferred[None]"]) -> None: 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: bytes) -> None: # 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: The hostname to send in the CONNECT message port: The port to send in the CONNECT message proxy_creds: credentials to authenticate at proxy """ def __init__( self, host: bytes, port: int, proxy_creds: Optional[ProxyCredentials], ): self.host = host self.port = port self.proxy_creds = proxy_creds self.on_connected: "defer.Deferred[None]" = defer.Deferred() def connectionMade(self) -> None: logger.debug("Connected to proxy, sending CONNECT") self.sendCommand(b"CONNECT", b"%s:%d" % (self.host, self.port)) # Determine whether we need to set Proxy-Authorization headers if self.proxy_creds: # Set a Proxy-Authorization header self.sendHeader( b"Proxy-Authorization", self.proxy_creds.as_proxy_authorization_value(), ) self.endHeaders() def handleStatus(self, version: bytes, status: bytes, message: bytes) -> None: logger.debug("Got Status: %s %s %s", status, message, version) if status != b"200": raise ProxyConnectError(f"Unexpected status on CONNECT: {status!s}") def handleEndHeaders(self) -> None: logger.debug("End Headers") self.on_connected.callback(None) def handleResponse(self, body: bytes) -> None: pass