Merge pull request #2369 from ujjwal96/stream-support

HTTP request & WebSocket message streaming

docs/features/passthrough.rst

@@ -16,7 +16,7 @@ mechanism:
 If you want to peek into (SSL-protected) non-HTTP connections, check out the :ref:`tcpproxy`
 feature.
 If you want to ignore traffic from mitmproxy's processing because of large response bodies,
-take a look at the :ref:`responsestreaming` feature.
+take a look at the :ref:`streaming` feature.
 
 How it works
 ------------
@@ -89,7 +89,7 @@ Here are some other examples for ignore patterns:
 .. seealso::
 
     - :ref:`tcpproxy`
-    - :ref:`responsestreaming`
+    - :ref:`streaming`
     - mitmproxy's "Limit" feature
 
 .. rubric:: Footnotes

docs/features/responsestreaming.rst

@@ -1,68 +0,0 @@
-.. _responsestreaming:
-
-Response Streaming
-==================
-
-By using mitmproxy's streaming feature, response contents can be passed to the client incrementally
-before they have been fully received by the proxy. This is especially useful for large binary files
-such as videos, where buffering the whole file slows down the client's browser.
-
-By default, mitmproxy will read the entire response, perform any indicated
-manipulations on it and then send the (possibly modified) response to
-the client. In some cases this is undesirable and you may wish to "stream"
-the response back to the client. When streaming is enabled, the response is
-not buffered on the proxy but directly sent back to the client instead.
-
-On the command-line
--------------------
-
-Streaming can be enabled on the command line for all response bodies exceeding a certain size.
-The SIZE argument understands k/m/g suffixes, e.g. 3m for 3 megabytes.
-
-================== =================
-command-line       ``--stream SIZE``
-================== =================
-
-.. warning::
-
-    When response streaming is enabled, **streamed response contents will not be
-    recorded or preserved in any way.**
-
-.. note::
-
-    When response streaming is enabled, the response body cannot be modified by the usual means.
-
-Customizing Response Streaming
-------------------------------
-
-You can also use a script to customize exactly which responses are streamed.
-
-Responses that should be tagged for streaming by setting their ``.stream``
-attribute to ``True``:
-
-.. literalinclude:: ../../examples/complex/stream.py
-   :caption: examples/complex/stream.py
-   :language: python
-
-Implementation Details
-----------------------
-
-When response streaming is enabled, portions of the code which would have otherwise performed
-changes on the response body will see an empty response body. Any modifications will be ignored.
-
-Streamed responses are usually sent in chunks of 4096 bytes. If the response is sent with a
-``Transfer-Encoding: chunked`` header, the response will be streamed one chunk at a time.
-
-Modifying streamed data
------------------------
-
-If the ``.stream`` attribute is callable, ``.stream`` will wrap the generator that yields all
-chunks.
-
-.. literalinclude:: ../../examples/complex/stream_modify.py
-   :caption: examples/complex/stream_modify.py
-   :language: python
-
-.. seealso::
-
-    - :ref:`passthrough`

docs/features/streaming.rst

@@ -0,0 +1,102 @@
+.. _streaming:
+
+HTTP Streaming
+==============
+
+By default, mitmproxy will read the entire request/response, perform any indicated
+manipulations on it and then send the (possibly modified) message to
+the other party. In some cases this is undesirable and you may wish to "stream"
+the request/response. When streaming is enabled, the request/response is
+not buffered on the proxy but directly sent to the server/client instead.
+HTTP headers are still fully buffered before being sent.
+
+Request Streaming
+-----------------
+
+Request streaming can be used to incrementally stream a request body to the server
+before it has been fully received by the proxy. This is useful for large file uploads.
+
+Response Streaming
+------------------
+
+By using mitmproxy's streaming feature, response contents can be passed to the client incrementally
+before they have been fully received by the proxy. This is especially useful for large binary files
+such as videos, where buffering the whole file slows down the client's browser.
+
+On the command-line
+-------------------
+
+Streaming can be enabled on the command line for all request and response bodies exceeding a certain size.
+The SIZE argument understands k/m/g suffixes, e.g. 3m for 3 megabytes.
+
+================== =================
+command-line       ``--set stream_large_bodies=SIZE``
+================== =================
+
+.. warning::
+
+    When streaming is enabled, **streamed request/response contents will not be
+    recorded or preserved in any way.**
+
+.. note::
+
+    When streaming is enabled, the request/response body cannot be modified by the usual means.
+
+Customizing Streaming
+---------------------
+
+You can also use a script to customize exactly which requests or responses are streamed.
+
+Requests/Responses that should be tagged for streaming by setting their ``.stream``
+attribute to ``True``:
+
+.. literalinclude:: ../../examples/complex/stream.py
+   :caption: examples/complex/stream.py
+   :language: python
+
+Implementation Details
+----------------------
+
+When response streaming is enabled, portions of the code which would have otherwise performed
+changes on the request/response body will see an empty body. Any modifications will be ignored.
+
+Streamed bodies are usually sent in chunks of 4096 bytes. If the response is sent with a
+``Transfer-Encoding: chunked`` header, the response will be streamed one chunk at a time.
+
+Modifying streamed data
+-----------------------
+
+If the ``.stream`` attribute is callable, ``.stream`` will wrap the generator that yields all
+chunks.
+
+.. literalinclude:: ../../examples/complex/stream_modify.py
+   :caption: examples/complex/stream_modify.py
+   :language: python
+
+WebSocket Streaming
+===================
+
+The WebSocket streaming feature can be used to send the frames as soon as they arrive. This can be useful for large binary file transfers.
+
+On the command-line
+-------------------
+
+Streaming can be enabled on the command line for all WebSocket frames
+
+================== =================
+command-line       ``--set stream_websockets=true``
+================== =================
+
+.. note::
+
+    When Web Socket streaming is enabled, the message payload cannot be modified.
+
+Implementation Details
+----------------------
+When WebSocket streaming is enabled, portions of the code which may perform changes to the WebSocket message payloads will not have
+any effect on the actual payload sent to the server as the frames are immediately forwarded to the server.
+In contrast to HTTP streaming, where the body is not stored, the message payload will still be stored in the WebSocket Flow.
+
+.. seealso::
+
+    - :ref:`passthrough`

docs/features/tcpproxy.rst

@@ -28,4 +28,4 @@ feature.
 .. seealso::
 
     - :ref:`passthrough`
-    - :ref:`responsestreaming`
+    - :ref:`streaming`

docs/index.rst

@@ -33,7 +33,7 @@
     features/passthrough
     features/proxyauth
     features/reverseproxy
-    features/responsestreaming
+    features/streaming
     features/socksproxy
     features/sticky
     features/tcpproxy

examples/complex/stream.py

@@ -1,6 +1,6 @@
 def responseheaders(flow):
     """
     Enables streaming for all responses.
-    This is equivalent to passing `--stream 0` to mitmproxy.
+    This is equivalent to passing `--set stream_large_bodies=1` to mitmproxy.
     """
     flow.response.stream = True

mitmproxy/addons/streambodies.py

@@ -28,12 +28,18 @@ class StreamBodies:
             if expected_size and not r.raw_content and not (0 <= expected_size <= self.max_size):
                 # r.stream may already be a callable, which we want to preserve.
                 r.stream = r.stream or True
-                # FIXME: make message generic when we add rquest streaming
-                ctx.log.info("Streaming response from %s" % f.request.host)
+                ctx.log.info("Streaming {} {}".format("response from" if not is_request else "request to", f.request.host))
 
-    # FIXME! Request streaming doesn't work at the moment.
     def requestheaders(self, f):
         self.run(f, True)
 
     def responseheaders(self, f):
         self.run(f, False)
+
+    def websocket_start(self, f):
+        if ctx.options.stream_websockets:
+            f.stream = True
+            ctx.log.info("Streaming WebSocket messages between {client} and {server}".format(
+                client=human.format_address(f.client_conn.address),
+                server=human.format_address(f.server_conn.address))
+            )

mitmproxy/options.py

@@ -154,6 +154,13 @@ class Options(optmanager.OptManager):
             Understands k/m/g suffixes, i.e. 3m for 3 megabytes.
             """
         )
+        self.add_option(
+            "stream_websockets", bool, False,
+            """
+            Stream WebSocket messages between client and server.
+            Messages are captured and cannot be modified.
+            """
+        )
         self.add_option(
             "verbosity", int, 2,
             "Log verbosity."

mitmproxy/proxy/protocol/http.py

@@ -273,7 +273,10 @@ class HttpLayer(base.Layer):
                 self.send_response(http.expect_continue_response)
                 request.headers.pop("expect")
 
-            request.data.content = b"".join(self.read_request_body(request))
+            if f.request.stream:
+                f.request.data.content = None
+            else:
+                f.request.data.content = b"".join(self.read_request_body(request))
             request.timestamp_end = time.time()
         except exceptions.HttpException as e:
             # We optimistically guess there might be an HTTP client on the
@@ -326,12 +329,8 @@ class HttpLayer(base.Layer):
                     f.request.scheme
                 )
 
-                def get_response():
-                    self.send_request(f.request)
-                    f.response = self.read_response_headers()
-
                 try:
-                    get_response()
+                    self.send_request_headers(f.request)
                 except exceptions.NetlibException as e:
                     self.log(
                         "server communication error: %s" % repr(e),
@@ -357,7 +356,19 @@ class HttpLayer(base.Layer):
 
                     self.disconnect()
                     self.connect()
-                    get_response()
+                    self.send_request_headers(f.request)
+
+                # This is taken out of the try except block because when streaming
+                # we can't send the request body while retrying as the generator gets exhausted
+                if f.request.stream:
+                    chunks = self.read_request_body(f.request)
+                    if callable(f.request.stream):
+                        chunks = f.request.stream(chunks)
+                    self.send_request_body(f.request, chunks)
+                else:
+                    self.send_request_body(f.request, [f.request.data.content])
+
+                f.response = self.read_response_headers()
 
                 # call the appropriate script hook - this is an opportunity for
                 # an inline script to set f.stream = True

mitmproxy/proxy/protocol/http1.py

@@ -22,6 +22,16 @@ class Http1Layer(httpbase._HttpTransmissionLayer):
             self.config.options._processed.get("body_size_limit")
         )
 
+    def send_request_headers(self, request):
+        headers = http1.assemble_request_head(request)
+        self.server_conn.wfile.write(headers)
+        self.server_conn.wfile.flush()
+
+    def send_request_body(self, request, chunks):
+        for chunk in http1.assemble_body(request.headers, chunks):
+            self.server_conn.wfile.write(chunk)
+            self.server_conn.wfile.flush()
+
     def send_request(self, request):
         self.server_conn.wfile.write(http1.assemble_request(request))
         self.server_conn.wfile.flush()

mitmproxy/proxy/protocol/http2.py

@@ -487,14 +487,23 @@ class Http2SingleStreamLayer(httpbase._HttpTransmissionLayer, basethread.BaseThr
 
     @detect_zombie_stream
     def read_request_body(self, request):
-        self.request_data_finished.wait()
-        data = []
-        while self.request_data_queue.qsize() > 0:
-            data.append(self.request_data_queue.get())
-        return data
+        if not request.stream:
+            self.request_data_finished.wait()
+
+        while True:
+            try:
+                yield self.request_data_queue.get(timeout=0.1)
+            except queue.Empty:  # pragma: no cover
+                pass
+            if self.request_data_finished.is_set():
+                self.raise_zombie()
+                while self.request_data_queue.qsize() > 0:
+                    yield self.request_data_queue.get()
+                break
+            self.raise_zombie()
 
     @detect_zombie_stream
-    def send_request(self, message):
+    def send_request_headers(self, request):
         if self.pushed:
             # nothing to do here
             return
@@ -519,10 +528,10 @@ class Http2SingleStreamLayer(httpbase._HttpTransmissionLayer, basethread.BaseThr
         self.server_stream_id = self.connections[self.server_conn].get_next_available_stream_id()
         self.server_to_client_stream_ids[self.server_stream_id] = self.client_stream_id
 
-        headers = message.headers.copy()
-        headers.insert(0, ":path", message.path)
-        headers.insert(0, ":method", message.method)
-        headers.insert(0, ":scheme", message.scheme)
+        headers = request.headers.copy()
+        headers.insert(0, ":path", request.path)
+        headers.insert(0, ":method", request.method)
+        headers.insert(0, ":scheme", request.scheme)
 
         priority_exclusive = None
         priority_depends_on = None
@@ -553,13 +562,24 @@ class Http2SingleStreamLayer(httpbase._HttpTransmissionLayer, basethread.BaseThr
             self.raise_zombie()
             self.connections[self.server_conn].lock.release()
 
+    @detect_zombie_stream
+    def send_request_body(self, request, chunks):
+        if self.pushed:
+            # nothing to do here
+            return
+
         if not self.no_body:
             self.connections[self.server_conn].safe_send_body(
                 self.raise_zombie,
                 self.server_stream_id,
-                [message.content]
+                chunks
             )
 
+    @detect_zombie_stream
+    def send_request(self, message):
+        self.send_request_headers(message)
+        self.send_request_body(message, [message.content])
+
     @detect_zombie_stream
     def read_response_headers(self):
         self.response_arrived.wait()

mitmproxy/proxy/protocol/websocket.py

@@ -55,6 +55,7 @@ class WebSocketLayer(base.Layer):
             return self._handle_unknown_frame(frame, source_conn, other_conn, is_server)
 
     def _handle_data_frame(self, frame, source_conn, other_conn, is_server):
+
         fb = self.server_frame_buffer if is_server else self.client_frame_buffer
         fb.append(frame)
 
@@ -70,43 +71,51 @@ class WebSocketLayer(base.Layer):
             self.flow.messages.append(websocket_message)
             self.channel.ask("websocket_message", self.flow)
 
-            def get_chunk(payload):
-                if len(payload) == length:
-                    # message has the same length, we can reuse the same sizes
-                    pos = 0
-                    for s in original_chunk_sizes:
-                        yield payload[pos:pos + s]
-                        pos += s
+            if not self.flow.stream:
+                def get_chunk(payload):
+                    if len(payload) == length:
+                        # message has the same length, we can reuse the same sizes
+                        pos = 0
+                        for s in original_chunk_sizes:
+                            yield payload[pos:pos + s]
+                            pos += s
+                    else:
+                        # just re-chunk everything into 4kB frames
+                        # header len = 4 bytes without masking key and 8 bytes with masking key
+                        chunk_size = 4092 if is_server else 4088
+                        chunks = range(0, len(payload), chunk_size)
+                        for i in chunks:
+                            yield payload[i:i + chunk_size]
+
+                frms = [
+                    websockets.Frame(
+                        payload=chunk,
+                        opcode=frame.header.opcode,
+                        mask=(False if is_server else 1),
+                        masking_key=(b'' if is_server else os.urandom(4)))
+                    for chunk in get_chunk(websocket_message.content)
+                ]
+
+                if len(frms) > 0:
+                    frms[-1].header.fin = True
                 else:
-                    # just re-chunk everything into 10kB frames
-                    chunk_size = 10240
-                    chunks = range(0, len(payload), chunk_size)
-                    for i in chunks:
-                        yield payload[i:i + chunk_size]
+                    frms.append(websockets.Frame(
+                        fin=True,
+                        opcode=websockets.OPCODE.CONTINUE,
+                        mask=(False if is_server else 1),
+                        masking_key=(b'' if is_server else os.urandom(4))))
 
-            frms = [
-                websockets.Frame(
-                    payload=chunk,
-                    opcode=frame.header.opcode,
-                    mask=(False if is_server else 1),
-                    masking_key=(b'' if is_server else os.urandom(4)))
-                for chunk in get_chunk(websocket_message.content)
-            ]
+                frms[0].header.opcode = message_type
+                frms[0].header.rsv1 = compressed_message
+
+                for frm in frms:
+                    other_conn.send(bytes(frm))
 
-            if len(frms) > 0:
-                frms[-1].header.fin = True
             else:
-                frms.append(websockets.Frame(
-                    fin=True,
-                    opcode=websockets.OPCODE.CONTINUE,
-                    mask=(False if is_server else 1),
-                    masking_key=(b'' if is_server else os.urandom(4))))
+                other_conn.send(bytes(frame))
 
-            frms[0].header.opcode = message_type
-            frms[0].header.rsv1 = compressed_message
-
-            for frm in frms:
-                other_conn.send(bytes(frm))
+        elif self.flow.stream:
+            other_conn.send(bytes(frame))
 
         return True
 

mitmproxy/websocket.py

@@ -45,6 +45,7 @@ class WebSocketFlow(flow.Flow):
         self.close_code = '(status code missing)'
         self.close_message = '(message missing)'
         self.close_reason = 'unknown status code'
+        self.stream = False
 
         if handshake_flow:
             self.client_key = websockets.get_client_key(handshake_flow.request.headers)

test/mitmproxy/addons/test_streambodies.py

@@ -29,3 +29,9 @@ def test_simple():
         f = tflow.tflow(resp=True)
         f.response.headers["content-length"] = "invalid"
         tctx.cycle(sa, f)
+
+        tctx.configure(sa, stream_websockets = True)
+        f = tflow.twebsocketflow()
+        assert not f.stream
+        sa.websocket_start(f)
+        assert f.stream

test/mitmproxy/proxy/protocol/test_http1.py

@@ -1,7 +1,6 @@
 from unittest import mock
 import pytest
 
-from mitmproxy import exceptions
 from mitmproxy.test import tflow
 from mitmproxy.net.http import http1
 from mitmproxy.net.tcp import TCPClient
@@ -108,9 +107,5 @@ class TestStreaming(tservers.HTTPProxyTest):
                 r = p.request("post:'%s/p/200:b@10000'" % self.server.urlbase)
                 assert len(r.content) == 10000
 
-                if streaming:
-                    with pytest.raises(exceptions.HttpReadDisconnect):  # as the assertion in assert_write fails
-                        # request with 10000 bytes
-                        p.request("post:'%s/p/200':b@10000" % self.server.urlbase)
-                else:
-                    assert p.request("post:'%s/p/200':b@10000" % self.server.urlbase)
+                # request with 10000 bytes
+                assert p.request("post:'%s/p/200':b@10000" % self.server.urlbase)

test/mitmproxy/proxy/protocol/test_http2.py

@@ -14,6 +14,7 @@ import mitmproxy.net
 from ...net import tservers as net_tservers
 from mitmproxy import exceptions
 from mitmproxy.net.http import http1, http2
+from pathod.language import generators
 
 from ... import tservers
 from ....conftest import requires_alpn
@@ -166,7 +167,8 @@ class _Http2TestBase:
                       end_stream=None,
                       priority_exclusive=None,
                       priority_depends_on=None,
-                      priority_weight=None):
+                      priority_weight=None,
+                      streaming=False):
         if headers is None:
             headers = []
         if end_stream is None:
@@ -182,7 +184,8 @@ class _Http2TestBase:
         )
         if body:
             h2_conn.send_data(stream_id, body)
-            h2_conn.end_stream(stream_id)
+            if not streaming:
+                h2_conn.end_stream(stream_id)
         wfile.write(h2_conn.data_to_send())
         wfile.flush()
 
@@ -862,3 +865,120 @@ class TestConnectionTerminated(_Http2Test):
         assert connection_terminated_event.error_code == 5
         assert connection_terminated_event.last_stream_id == 42
         assert connection_terminated_event.additional_data == b'foobar'
+
+
+@requires_alpn
+class TestRequestStreaming(_Http2Test):
+
+    @classmethod
+    def handle_server_event(cls, event, h2_conn, rfile, wfile):
+        if isinstance(event, h2.events.ConnectionTerminated):
+            return False
+        elif isinstance(event, h2.events.DataReceived):
+            data = event.data
+            assert data
+            h2_conn.close_connection(error_code=5, last_stream_id=42, additional_data=data)
+            wfile.write(h2_conn.data_to_send())
+            wfile.flush()
+
+        return True
+
+    @pytest.mark.parametrize('streaming', [True, False])
+    def test_request_streaming(self, streaming):
+        class Stream:
+            def requestheaders(self, f):
+                f.request.stream = streaming
+
+        self.master.addons.add(Stream())
+        h2_conn = self.setup_connection()
+        body = generators.RandomGenerator("bytes", 100)[:]
+        self._send_request(
+            self.client.wfile,
+            h2_conn,
+            headers=[
+                (':authority', "127.0.0.1:{}".format(self.server.server.address[1])),
+                (':method', 'GET'),
+                (':scheme', 'https'),
+                (':path', '/'),
+
+            ],
+            body=body,
+            streaming=True
+        )
+        done = False
+        connection_terminated_event = None
+        self.client.rfile.o.settimeout(2)
+        while not done:
+            try:
+                raw = b''.join(http2.read_raw_frame(self.client.rfile))
+                events = h2_conn.receive_data(raw)
+
+                for event in events:
+                    if isinstance(event, h2.events.ConnectionTerminated):
+                        connection_terminated_event = event
+                        done = True
+            except:
+                break
+
+        if streaming:
+            assert connection_terminated_event.additional_data == body
+        else:
+            assert connection_terminated_event is None
+
+
+@requires_alpn
+class TestResponseStreaming(_Http2Test):
+
+    @classmethod
+    def handle_server_event(cls, event, h2_conn, rfile, wfile):
+        if isinstance(event, h2.events.ConnectionTerminated):
+            return False
+        elif isinstance(event, h2.events.RequestReceived):
+            data = generators.RandomGenerator("bytes", 100)[:]
+            h2_conn.send_headers(event.stream_id, [
+                (':status', '200'),
+                ('content-length', '100')
+            ])
+            h2_conn.send_data(event.stream_id, data)
+            wfile.write(h2_conn.data_to_send())
+            wfile.flush()
+        return True
+
+    @pytest.mark.parametrize('streaming', [True, False])
+    def test_response_streaming(self, streaming):
+        class Stream:
+            def responseheaders(self, f):
+                f.response.stream = streaming
+
+        self.master.addons.add(Stream())
+        h2_conn = self.setup_connection()
+        self._send_request(
+            self.client.wfile,
+            h2_conn,
+            headers=[
+                (':authority', "127.0.0.1:{}".format(self.server.server.address[1])),
+                (':method', 'GET'),
+                (':scheme', 'https'),
+                (':path', '/'),
+
+            ]
+        )
+        done = False
+        self.client.rfile.o.settimeout(2)
+        data = None
+        while not done:
+            try:
+                raw = b''.join(http2.read_raw_frame(self.client.rfile))
+                events = h2_conn.receive_data(raw)
+
+                for event in events:
+                    if isinstance(event, h2.events.DataReceived):
+                        data = event.data
+                        done = True
+            except:
+                break
+
+        if streaming:
+            assert data
+        else:
+            assert data is None

test/mitmproxy/proxy/protocol/test_websocket.py

@@ -155,7 +155,13 @@ class TestSimple(_WebSocketTest):
         wfile.write(bytes(frame))
         wfile.flush()
 
-    def test_simple(self):
+    @pytest.mark.parametrize('streaming', [True, False])
+    def test_simple(self, streaming):
+        class Stream:
+            def websocket_start(self, f):
+                f.stream = streaming
+
+        self.master.addons.add(Stream())
         self.setup_connection()
 
         frame = websockets.Frame.from_file(self.client.rfile)
@@ -328,3 +334,32 @@ class TestInvalidFrame(_WebSocketTest):
         frame = websockets.Frame.from_file(self.client.rfile)
         assert frame.header.opcode == 15
         assert frame.payload == b'foobar'
+
+
+class TestStreaming(_WebSocketTest):
+
+    @classmethod
+    def handle_websockets(cls, rfile, wfile):
+        wfile.write(bytes(websockets.Frame(opcode=websockets.OPCODE.TEXT, payload=b'server-foobar')))
+        wfile.flush()
+
+    @pytest.mark.parametrize('streaming', [True, False])
+    def test_streaming(self, streaming):
+        class Stream:
+            def websocket_start(self, f):
+                f.stream = streaming
+
+        self.master.addons.add(Stream())
+        self.setup_connection()
+
+        frame = None
+        if not streaming:
+            with pytest.raises(exceptions.TcpDisconnect):  # Reader.safe_read get nothing as result
+                frame = websockets.Frame.from_file(self.client.rfile)
+            assert frame is None
+
+        else:
+            frame = websockets.Frame.from_file(self.client.rfile)
+
+            assert frame
+            assert self.master.state.flows[1].messages == []  # Message not appended as the final frame isn't received

test/mitmproxy/proxy/test_server.py

@@ -239,13 +239,28 @@ class TestHTTP(tservers.HTTPProxyTest, CommonMixin):
                 p.request("get:'%s'" % response)
 
     def test_reconnect(self):
-        req = "get:'%s/p/200:b@1:da'" % self.server.urlbase
+        req = "get:'%s/p/200:b@1'" % self.server.urlbase
         p = self.pathoc()
+
+        class MockOnce:
+            call = 0
+
+            def mock_once(self, http1obj, req):
+                self.call += 1
+                if self.call == 1:
+                    raise exceptions.TcpDisconnect
+                else:
+                    headers = http1.assemble_request_head(req)
+                    http1obj.server_conn.wfile.write(headers)
+                    http1obj.server_conn.wfile.flush()
+
         with p.connect():
-            assert p.request(req)
-            # Server has disconnected. Mitmproxy should detect this, and reconnect.
-            assert p.request(req)
-            assert p.request(req)
+            with mock.patch("mitmproxy.proxy.protocol.http1.Http1Layer.send_request_headers",
+                            side_effect=MockOnce().mock_once, autospec=True):
+                # Server disconnects while sending headers but mitmproxy reconnects
+                resp = p.request(req)
+                assert resp
+                assert resp.status_code == 200
 
     def test_get_connection_switching(self):
         req = "get:'%s/p/200:b@1'"
@@ -1072,6 +1087,23 @@ class TestProxyChainingSSLReconnect(tservers.HTTPUpstreamProxyTest):
         proxified to an upstream http proxy, we need to send the CONNECT
         request again.
         """
+
+        class MockOnce:
+            call = 0
+
+            def mock_once(self, http1obj, req):
+                self.call += 1
+
+                if self.call == 2:
+                    headers = http1.assemble_request_head(req)
+                    http1obj.server_conn.wfile.write(headers)
+                    http1obj.server_conn.wfile.flush()
+                    raise exceptions.TcpDisconnect
+                else:
+                    headers = http1.assemble_request_head(req)
+                    http1obj.server_conn.wfile.write(headers)
+                    http1obj.server_conn.wfile.flush()
+
         self.chain[0].tmaster.addons.add(RequestKiller([1, 2]))
         self.chain[1].tmaster.addons.add(RequestKiller([1]))
 
@@ -1086,7 +1118,10 @@ class TestProxyChainingSSLReconnect(tservers.HTTPUpstreamProxyTest):
             assert len(self.chain[0].tmaster.state.flows) == 1
             assert len(self.chain[1].tmaster.state.flows) == 1
 
-            req = p.request("get:'/p/418:b\"content2\"'")
+            with mock.patch("mitmproxy.proxy.protocol.http1.Http1Layer.send_request_headers",
+                            side_effect=MockOnce().mock_once, autospec=True):
+                req = p.request("get:'/p/418:b\"content2\"'")
+
             assert req.status_code == 502
 
             assert len(self.proxy.tmaster.state.flows) == 2