ignore superfluous newlines after HTTP CONNECT, fix #4870 (#4871)

mitmproxy/proxy/layers/http/__init__.py

@@ -592,11 +592,11 @@ class HttpStream(layer.Layer):
             )
 
         if 200 <= self.flow.response.status_code < 300:
-            yield SendHttp(ResponseHeaders(self.stream_id, self.flow.response, True), self.context.client)
-            yield SendHttp(ResponseEndOfMessage(self.stream_id), self.context.client)
             self.child_layer = self.child_layer or layer.NextLayer(self.context)
             yield from self.child_layer.handle_event(events.Start())
             self._handle_event = self.passthrough
+            yield SendHttp(ResponseHeaders(self.stream_id, self.flow.response, True), self.context.client)
+            yield SendHttp(ResponseEndOfMessage(self.stream_id), self.context.client)
         else:
             yield from self.send_response()
 

mitmproxy/proxy/layers/http/_http1.py

@@ -122,7 +122,10 @@ class Http1Connection(HttpConnection, metaclass=abc.ABCMeta):
         self.state = self.passthrough
         if self.buf:
             already_received = self.buf.maybe_extract_at_most(len(self.buf))
-            yield from self.state(events.DataReceived(self.conn, already_received))
+            # Some clients send superfluous newlines after CONNECT, we want to eat those.
+            already_received = already_received.lstrip(b"\r\n")
+            if already_received:
+                yield from self.state(events.DataReceived(self.conn, already_received))
 
     def passthrough(self, event: events.Event) -> layer.CommandGenerator[None]:
         assert self.stream_id

test/mitmproxy/proxy/layers/http/test_http.py

@@ -1324,3 +1324,23 @@ def test_chunked_and_content_length_set_by_addon(tctx):
                                      b"Transfer-Encoding: chunked\r\n\r\n"
                                      b"0\r\n\r\n")
     )
+
+
+def test_connect_more_newlines(tctx):
+    """Ignore superfluous \r\n in CONNECT request, https://github.com/mitmproxy/mitmproxy/issues/4870"""
+    server = Placeholder(Server)
+    playbook = Playbook(http.HttpLayer(tctx, HTTPMode.regular))
+    nl = Placeholder(layer.NextLayer)
+
+    assert (
+        playbook
+        >> DataReceived(tctx.client, b"CONNECT example.com:80 HTTP/1.1\r\n\r\n\r\n")
+        << http.HttpConnectHook(Placeholder())
+        >> reply()
+        << OpenConnection(server)
+        >> reply(None)
+        << SendData(tctx.client, b'HTTP/1.1 200 Connection established\r\n\r\n')
+        >> DataReceived(tctx.client, b"\x16\x03\x03\x00\xb3\x01\x00\x00\xaf\x03\x03")
+        << layer.NextLayerHook(nl)
+    )
+    assert nl().data_client() == b"\x16\x03\x03\x00\xb3\x01\x00\x00\xaf\x03\x03"