from __future__ import (absolute_import, print_function, division) import sys import traceback import six from netlib import tcp from netlib.exceptions import HttpException, HttpReadDisconnect, NetlibException from netlib.http import Headers, CONTENT_MISSING from h2.exceptions import H2Error from .. import utils from ..exceptions import HttpProtocolException, ProtocolException from ..models import ( HTTPFlow, HTTPResponse, make_error_response, make_connect_response, Error, expect_continue_response ) from .base import Layer, Kill class _HttpTransmissionLayer(Layer): def read_request(self): raise NotImplementedError() def read_request_body(self, request): raise NotImplementedError() def send_request(self, request): raise NotImplementedError() def read_response(self, request): response = self.read_response_headers() response.data.content = b"".join( self.read_response_body(request, response) ) return response def read_response_headers(self): raise NotImplementedError() def read_response_body(self, request, response): raise NotImplementedError() yield "this is a generator" # pragma: no cover def send_response(self, response): if response.content == CONTENT_MISSING: raise HttpException("Cannot assemble flow with CONTENT_MISSING") self.send_response_headers(response) self.send_response_body(response, [response.content]) def send_response_headers(self, response): raise NotImplementedError() def send_response_body(self, response, chunks): raise NotImplementedError() def check_close_connection(self, flow): raise NotImplementedError() class ConnectServerConnection(object): """ "Fake" ServerConnection to represent state after a CONNECT request to an upstream proxy. """ def __init__(self, address, ctx): self.address = tcp.Address.wrap(address) self._ctx = ctx @property def via(self): return self._ctx.server_conn def __getattr__(self, item): return getattr(self.via, item) def __nonzero__(self): return bool(self.via) class UpstreamConnectLayer(Layer): def __init__(self, ctx, connect_request): super(UpstreamConnectLayer, self).__init__(ctx) self.connect_request = connect_request self.server_conn = ConnectServerConnection( (connect_request.host, connect_request.port), self.ctx ) def __call__(self): layer = self.ctx.next_layer(self) layer() def _send_connect_request(self): self.send_request(self.connect_request) resp = self.read_response(self.connect_request) if resp.status_code != 200: raise ProtocolException("Reconnect: Upstream server refuses CONNECT request") def connect(self): if not self.server_conn: self.ctx.connect() self._send_connect_request() else: pass # swallow the message def change_upstream_proxy_server(self, address): if address != self.server_conn.via.address: self.ctx.set_server(address) def set_server(self, address, server_tls=None, sni=None): if self.ctx.server_conn: self.ctx.disconnect() address = tcp.Address.wrap(address) self.connect_request.host = address.host self.connect_request.port = address.port self.server_conn.address = address if server_tls: raise ProtocolException( "Cannot upgrade to TLS, no TLS layer on the protocol stack." ) class HttpLayer(Layer): def __init__(self, ctx, mode): super(HttpLayer, self).__init__(ctx) self.mode = mode self.__original_server_conn = None "Contains the original destination in transparent mode, which needs to be restored" "if an inline script modified the target server for a single http request" def __call__(self): if self.mode == "transparent": self.__original_server_conn = self.server_conn while True: try: request = self.get_request_from_client() self.log("request", "debug", [repr(request)]) # Handle Proxy Authentication # Proxy Authentication conceptually does not work in transparent mode. # We catch this misconfiguration on startup. Here, we sort out requests # after a successful CONNECT request (which do not need to be validated anymore) if self.mode != "transparent" and not self.authenticate(request): return # Make sure that the incoming request matches our expectations self.validate_request(request) # Regular Proxy Mode: Handle CONNECT if self.mode == "regular" and request.form_in == "authority": self.handle_regular_mode_connect(request) return except HttpReadDisconnect: # don't throw an error for disconnects that happen before/between requests. return except NetlibException as e: self.send_error_response(400, repr(e)) six.reraise(ProtocolException, ProtocolException( "Error in HTTP connection: %s" % repr(e)), sys.exc_info()[2]) try: flow = HTTPFlow(self.client_conn, self.server_conn, live=self) flow.request = request self.process_request_hook(flow) if not flow.response: self.establish_server_connection(flow) self.get_response_from_server(flow) else: # response was set by an inline script. # we now need to emulate the responseheaders hook. flow = self.channel.ask("responseheaders", flow) if flow == Kill: raise Kill() self.log("response", "debug", [repr(flow.response)]) flow = self.channel.ask("response", flow) if flow == Kill: raise Kill() self.send_response_to_client(flow) if self.check_close_connection(flow): return # Handle 101 Switching Protocols # It may be useful to pass additional args (such as the upgrade header) # to next_layer in the future if flow.response.status_code == 101: layer = self.ctx.next_layer(self) layer() return # Upstream Proxy Mode: Handle CONNECT if flow.request.form_in == "authority" and flow.response.status_code == 200: self.handle_upstream_mode_connect(flow.request.copy()) return except (ProtocolException, NetlibException) as e: self.send_error_response(502, repr(e)) if not flow.response: flow.error = Error(str(e)) self.channel.ask("error", flow) self.log(traceback.format_exc(), "debug") return else: six.reraise(ProtocolException, ProtocolException( "Error in HTTP connection: %s" % repr(e)), sys.exc_info()[2]) finally: flow.live = False def get_request_from_client(self): request = self.read_request() if request.headers.get("expect", "").lower() == "100-continue": # TODO: We may have to use send_response_headers for HTTP2 here. self.send_response(expect_continue_response) request.headers.pop("expect") request.body = b"".join(self.read_request_body(request)) return request def send_error_response(self, code, message): try: response = make_error_response(code, message) self.send_response(response) except NetlibException as H2Error: pass def change_upstream_proxy_server(self, address): # Make set_upstream_proxy_server always available, # even if there's no UpstreamConnectLayer if address != self.server_conn.address: return self.set_server(address) def handle_regular_mode_connect(self, request): self.set_server((request.host, request.port)) self.send_response(make_connect_response(request.http_version)) layer = self.ctx.next_layer(self) layer() def handle_upstream_mode_connect(self, connect_request): layer = UpstreamConnectLayer(self, connect_request) layer() def send_response_to_client(self, flow): if not flow.response.stream: # no streaming: # we already received the full response from the server and can # send it to the client straight away. self.send_response(flow.response) else: # streaming: # First send the headers and then transfer the response incrementally self.send_response_headers(flow.response) chunks = self.read_response_body( flow.request, flow.response ) if callable(flow.response.stream): chunks = flow.response.stream(chunks) self.send_response_body(flow.response, chunks) flow.response.timestamp_end = utils.timestamp() def get_response_from_server(self, flow): def get_response(): self.send_request(flow.request) flow.response = self.read_response_headers() try: get_response() except NetlibException as v: self.log( "server communication error: %s" % repr(v), level="debug" ) # In any case, we try to reconnect at least once. This is # necessary because it might be possible that we already # initiated an upstream connection after clientconnect that # has already been expired, e.g consider the following event # log: # > clientconnect (transparent mode destination known) # > serverconnect (required for client tls handshake) # > read n% of large request # > server detects timeout, disconnects # > read (100-n)% of large request # > send large request upstream self.disconnect() self.connect() get_response() # call the appropriate script hook - this is an opportunity for an # inline script to set flow.stream = True flow = self.channel.ask("responseheaders", flow) if flow == Kill: raise Kill() if flow.response.stream: flow.response.data.content = CONTENT_MISSING else: flow.response.data.content = b"".join(self.read_response_body( flow.request, flow.response )) flow.response.timestamp_end = utils.timestamp() # no further manipulation of self.server_conn beyond this point # we can safely set it as the final attribute value here. flow.server_conn = self.server_conn def process_request_hook(self, flow): # Determine .scheme, .host and .port attributes for inline scripts. # For absolute-form requests, they are directly given in the request. # For authority-form requests, we only need to determine the request scheme. # For relative-form requests, we need to determine host and port as # well. if self.mode == "regular": pass # only absolute-form at this point, nothing to do here. elif self.mode == "upstream": if flow.request.form_in == "authority": flow.request.scheme = "http" # pseudo value else: # Setting request.host also updates the host header, which we want to preserve host_header = flow.request.headers.get("host", None) flow.request.host = self.__original_server_conn.address.host flow.request.port = self.__original_server_conn.address.port if host_header: flow.request.headers["host"] = host_header # TODO: This does not really work if we change the first request and --no-upstream-cert is enabled flow.request.scheme = "https" if self.__original_server_conn.tls_established else "http" request_reply = self.channel.ask("request", flow) if request_reply == Kill: raise Kill() if isinstance(request_reply, HTTPResponse): flow.response = request_reply return def establish_server_connection(self, flow): address = tcp.Address((flow.request.host, flow.request.port)) tls = (flow.request.scheme == "https") if self.mode == "regular" or self.mode == "transparent": # If there's an existing connection that doesn't match our expectations, kill it. if address != self.server_conn.address or tls != self.server_conn.tls_established: self.set_server(address, tls, address.host) # Establish connection is neccessary. if not self.server_conn: self.connect() else: if not self.server_conn: self.connect() if tls: raise HttpProtocolException("Cannot change scheme in upstream proxy mode.") """ # This is a very ugly (untested) workaround to solve a very ugly problem. if self.server_conn and self.server_conn.tls_established and not ssl: self.disconnect() self.connect() elif ssl and not hasattr(self, "connected_to") or self.connected_to != address: if self.server_conn.tls_established: self.disconnect() self.connect() self.send_request(make_connect_request(address)) tls_layer = TlsLayer(self, False, True) tls_layer._establish_tls_with_server() """ def validate_request(self, request): if request.form_in == "absolute" and request.scheme != "http": raise HttpException("Invalid request scheme: %s" % request.scheme) expected_request_forms = { "regular": ("authority", "absolute",), "upstream": ("authority", "absolute"), "transparent": ("relative",) } allowed_request_forms = expected_request_forms[self.mode] if request.form_in not in allowed_request_forms: err_message = "Invalid HTTP request form (expected: %s, got: %s)" % ( " or ".join(allowed_request_forms), request.form_in ) raise HttpException(err_message) if self.mode == "regular" and request.form_in == "absolute": request.form_out = "relative" def authenticate(self, request): if self.config.authenticator: if self.config.authenticator.authenticate(request.headers): self.config.authenticator.clean(request.headers) else: self.send_response(make_error_response( 407, "Proxy Authentication Required", Headers(**self.config.authenticator.auth_challenge_headers()) )) return False return True