[sans-io] upstream proxy tests and fixes

mitmproxy/proxy2/context.py

@@ -54,7 +54,7 @@ class Client(Connection):
 class Server(Connection):
     sni = True
     """True: client SNI, False: no SNI, bytes: custom value"""
-    via: Sequence["Server"] = ()
+    via: Sequence[server_spec.ServerSpec] = ()
 
     def __init__(self, address: Optional[tuple]):
         self.address = address

mitmproxy/proxy2/layers/http/__init__.py

@@ -8,7 +8,7 @@ from mitmproxy.proxy.protocol.http import HTTPMode
 from mitmproxy.proxy2 import commands, events, layer, tunnel
 from mitmproxy.proxy2.context import Connection, Context, Server
 from mitmproxy.proxy2.layers import tls
-from mitmproxy.proxy2.layers.http import upstream_proxy
+from mitmproxy.proxy2.layers.http import _upstream_proxy
 from mitmproxy.proxy2.utils import expect
 from mitmproxy.utils import human
 from ._base import HttpCommand, HttpConnection, ReceiveHttp, StreamId
@@ -29,7 +29,7 @@ class GetHttpConnection(HttpCommand):
     tls: bool
     via: typing.Sequence[server_spec.ServerSpec]
 
-    def __init__(self, address: typing.Tuple[str, int], tls: bool, via: typing.Sequence[str]):
+    def __init__(self, address: typing.Tuple[str, int], tls: bool, via: typing.Sequence[server_spec.ServerSpec]):
         self.address = address
         self.tls = tls
         self.via = tuple(via)
@@ -116,38 +116,33 @@ class HttpStream(layer.Layer):
         )
         self.flow.request = event.request
 
-        if self.flow.request.first_line_format == "authority":
-            yield from self.handle_connect()
-            return
-
         if self.flow.request.headers.get("expect", "").lower() == "100-continue":
             raise NotImplementedError("expect nothing")
             # self.send_response(http.expect_continue_response)
             # request.headers.pop("expect")
 
-        # set first line format to relative in regular mode,
-        # see https://github.com/mitmproxy/mitmproxy/issues/1759
-        if self.mode is HTTPMode.regular and self.flow.request.first_line_format == "absolute":
-            self.flow.request.first_line_format = "relative"
+        if self.flow.request.first_line_format == "authority":
+            yield from self.handle_connect()
+            return
 
-        # update host header in reverse proxy mode
-        if self.context.options.mode.startswith("reverse:") and not self.context.options.keep_host_header:
-            self.flow.request.host_header = self.context.server.address[0]
-
-        # 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 is HTTPMode.transparent:
-            # Setting request.host also updates the host header, which we want
-            # to preserve
+        # Determine .scheme, .host and .port attributes for relative-form requests
+        if self.flow.request.first_line_format in "relative":
+            # Setting request.host also updates the host header, which we want to preserve
             host_header = self.flow.request.host_header
             self.flow.request.host = self.context.server.address[0]
             self.flow.request.port = self.context.server.address[1]
             self.flow.request.host_header = host_header  # set again as .host overwrites this.
             self.flow.request.scheme = "https" if self.context.server.tls else "http"
 
+        # set first line format to relative in regular mode,
+        # see https://github.com/mitmproxy/mitmproxy/issues/1759
+        if self.context.options.mode == "regular" and self.flow.request.first_line_format == "absolute":
+            self.flow.request.first_line_format = "relative"
+
+        # update host header in reverse proxy mode
+        if self.context.options.mode.startswith("reverse:") and not self.context.options.keep_host_header:
+            self.flow.request.host_header = self.context.server.address[0]
+
         self.flow.request.via = []  # FIXME: Make this an official attribute.
         if self.context.options.mode.startswith("upstream:"):
             self.flow.request.via.append(
@@ -272,7 +267,13 @@ class HttpStream(layer.Layer):
         yield HttpConnectHook(self.flow)
 
         self.context.server = Server((self.flow.request.host, self.flow.request.port))
-        if self.context.options.connection_strategy == "eager":
+
+        # We must not connect to the actual destination in upstream mode.
+        connect_now = (
+                self.context.options.connection_strategy == "eager"
+                and not self.context.options.mode.startswith("upstream:")
+        )
+        if connect_now:
             err = yield commands.OpenConnection(self.context.server)
             if err:
                 self.flow.response = http.HTTPResponse.make(
@@ -426,13 +427,17 @@ class HttpLayer(layer.Layer):
 
         if not can_reuse_context_connection:
             context.server = Server(event.address)
+            context.server.via = event.via
             if context.options.http2:
                 context.server.alpn_offers = tls.HTTP_ALPNS
             else:
                 context.server.alpn_offers = tls.HTTP1_ALPNS
 
             for via in reversed(event.via):
-                stack /= upstream_proxy.HttpUpstreamProxy(context, via.address)
+                needs_http_connect = (
+                        self.mode != HTTPMode.regular or via != event.via[-1]
+                )
+                stack /= _upstream_proxy.HttpUpstreamProxy(context, via.address, needs_http_connect)
             if event.tls:
                 stack /= tls.ServerTLSLayer(context)
 

mitmproxy/proxy2/layers/http/_upstream_proxy.py

@@ -5,25 +5,33 @@ from h11._receivebuffer import ReceiveBuffer
 from mitmproxy import http
 from mitmproxy.net.http import http1
 from mitmproxy.net.http.http1 import read_sansio as http1_sansio
-from mitmproxy.proxy2 import commands, context, events, layer, tunnel
+from mitmproxy.proxy2 import commands, context, layer, tunnel
 from mitmproxy.utils import human
 
 
 class HttpUpstreamProxy(tunnel.TunnelLayer):
     buf: ReceiveBuffer
+    send_connect: bool
 
-    def __init__(self, ctx: context.Context, address: tuple):
-        s = context.Server(address)
-        ctx.server.via = (*ctx.server.via, s)
-        super().__init__(ctx, tunnel_connection=s, conn=ctx.server)
+    def __init__(self, ctx: context.Context, address: tuple, send_connect: bool):
+        super().__init__(
+            ctx,
+            tunnel_connection=context.Server(address),
+            conn=ctx.server
+        )
         self.buf = ReceiveBuffer()
+        self.send_connect = send_connect
 
     def start_handshake(self) -> layer.CommandGenerator[None]:
+        if not self.send_connect:
+            return (yield from super().start_handshake())
         req = http.make_connect_request(self.conn.address)
         raw = http1.assemble_request(req)
         yield commands.SendData(self.tunnel_connection, raw)
 
     def receive_handshake_data(self, data: bytes) -> layer.CommandGenerator[Tuple[bool, Optional[str]]]:
+        if not self.send_connect:
+            return (yield from super().receive_handshake_data(data))
         self.buf += data
         response_head = self.buf.maybe_extract_lines()
         if response_head:

mitmproxy/proxy2/tunnel.py

@@ -49,6 +49,7 @@ class TunnelLayer(layer.Layer):
                 if self.tunnel_state is TunnelState.ESTABLISHING:
                     done, err = yield from self.receive_handshake_data(event.data)
                     if done:
+                        self.conn.state = context.ConnectionState.OPEN
                         self.tunnel_state = TunnelState.OPEN
                     if err:
                         self.tunnel_state = TunnelState.CLOSED
@@ -84,7 +85,6 @@ class TunnelLayer(layer.Layer):
                     if err:
                         yield from self.event_to_child(events.OpenConnectionReply(command, err))
                     else:
-                        self.conn.state = context.ConnectionState.OPEN
                         self.command_to_reply_to = command
                         yield from self.start_handshake()
                 else:

test/mitmproxy/proxy2/layers/test_http.py

@@ -1,6 +1,7 @@
 import pytest
 
 from mitmproxy.http import HTTPFlow, HTTPResponse
+from mitmproxy.net import server_spec
 from mitmproxy.proxy.protocol.http import HTTPMode
 from mitmproxy.proxy2 import layer
 from mitmproxy.proxy2.commands import CloseConnection, OpenConnection, SendData
@@ -345,3 +346,107 @@ def test_server_aborts(tctx, data):
     )
     assert flow().error
     assert b"502 Bad Gateway" in err()
+
+
+@pytest.mark.parametrize("redirect", [None, "proxy", "destination"])
+@pytest.mark.parametrize("scheme", ["http", "https"])
+@pytest.mark.parametrize("strategy", ["eager", "lazy"])
+def test_upstream_proxy(tctx, redirect, scheme, strategy):
+    """Test that an upstream HTTP proxy is used."""
+    server = Placeholder()
+    server2 = Placeholder()
+    flow = Placeholder()
+    tctx.options.mode = "upstream:http://proxy:8080"
+    tctx.options.connection_strategy = strategy
+    playbook = Playbook(http.HttpLayer(tctx, HTTPMode.regular), hooks=False)
+
+    if scheme == "http":
+        playbook >> DataReceived(tctx.client, b"GET http://example.com/ HTTP/1.1\r\nHost: example.com\r\n\r\n")
+        playbook << OpenConnection(server)
+        playbook >> reply(None)
+        # FIXME: We really shouldn't have the port here.
+        playbook << SendData(server, b"GET http://example.com:80/ HTTP/1.1\r\nHost: example.com\r\n\r\n")
+    else:
+        playbook >> DataReceived(tctx.client, b"CONNECT example.com:443 HTTP/1.1\r\n\r\n")
+        playbook << SendData(tctx.client, b"HTTP/1.1 200 Connection established\r\n\r\n")
+        playbook >> DataReceived(tctx.client, b"GET / HTTP/1.1\r\nHost: example.com\r\n\r\n")
+        playbook << layer.NextLayerHook(Placeholder())
+        playbook >> reply_next_layer(lambda ctx: http.HttpLayer(ctx, HTTPMode.transparent))
+        playbook << OpenConnection(server)
+        playbook >> reply(None)
+        playbook << SendData(server, b"CONNECT example.com:443 HTTP/1.1\r\n\r\n")
+        playbook >> DataReceived(server, b"HTTP/1.1 200 Connection established\r\n\r\n")
+        playbook << SendData(server, b"GET / HTTP/1.1\r\nHost: example.com\r\n\r\n")
+
+    playbook >> DataReceived(server, b"HTTP/1.1 418 OK\r\nContent-Length: 0\r\n\r\n")
+    playbook << SendData(tctx.client, b"HTTP/1.1 418 OK\r\nContent-Length: 0\r\n\r\n")
+
+    assert playbook
+    assert server().address == ("proxy", 8080)
+
+    if scheme == "http":
+        playbook >> DataReceived(tctx.client, b"GET http://example.com/two HTTP/1.1\r\nHost: example.com\r\n\r\n")
+    else:
+        playbook >> DataReceived(tctx.client, b"GET /two HTTP/1.1\r\nHost: example.com\r\n\r\n")
+
+    assert (playbook << http.HttpRequestHook(flow))
+    if redirect == "proxy":
+        flow().request.via = [server_spec.ServerSpec("http", ("other-proxy", 1234))]
+    elif redirect == "destination":
+        flow().request.host = "other-server"
+        flow().request.host_header = "example.com"
+    playbook >> reply()
+
+    if redirect:
+        # Protocol-wise we wouldn't need to open a new connection for plain http host redirects,
+        # but we disregard this edge case to simplify implementation.
+        playbook << OpenConnection(server2)
+        playbook >> reply(None)
+    else:
+        server2 = server
+
+    if scheme == "http":
+        if redirect == "destination":
+            playbook << SendData(server2, b"GET http://other-server:80/two HTTP/1.1\r\nHost: example.com\r\n\r\n")
+        else:
+            playbook << SendData(server2, b"GET http://example.com:80/two HTTP/1.1\r\nHost: example.com\r\n\r\n")
+    else:
+        if redirect:
+            if redirect == "destination":
+                playbook << SendData(server2, b"CONNECT other-server:443 HTTP/1.1\r\n\r\n")
+            else:
+                playbook << SendData(server2, b"CONNECT example.com:443 HTTP/1.1\r\n\r\n")
+            playbook >> DataReceived(server2, b"HTTP/1.1 200 Connection established\r\n\r\n")
+        playbook << SendData(server2, b"GET /two HTTP/1.1\r\nHost: example.com\r\n\r\n")
+
+    playbook >> DataReceived(server2, b"HTTP/1.1 418 OK\r\nContent-Length: 0\r\n\r\n")
+    playbook << SendData(tctx.client, b"HTTP/1.1 418 OK\r\nContent-Length: 0\r\n\r\n")
+
+    assert playbook
+
+    if redirect == "proxy":
+        assert server2().address == ("other-proxy", 1234)
+    else:
+        assert server2().address == ("proxy", 8080)
+
+    assert (
+            playbook
+            >> ConnectionClosed(tctx.client)
+            << CloseConnection(tctx.client)
+    )
+
+
+@pytest.mark.xfail(reason="h11 enforces host headers by default")
+def test_no_headers(tctx):
+    """Test that we can correctly reassemble requests/responses with no headers."""
+    server = Placeholder()
+    assert (
+            Playbook(http.HttpLayer(tctx, HTTPMode.regular), hooks=False)
+            >> DataReceived(tctx.client, b"GET http://example.com/ HTTP/1.1\r\n\r\n")
+            << OpenConnection(server)
+            >> reply(None)
+            << SendData(server, b"GET / HTTP/1.1\r\n\r\n")
+            >> DataReceived(server, b"HTTP/1.1 204 No Content\r\n\r\n")
+            << SendData(tctx.client, b"HTTP/1.1 204 No Content\r\n\r\n")
+    )
+    assert server().address == ("example.com", 80)