ASGIApp should ignore the HTTP flows loaded from somewhere (#4324)

CHANGELOG.rst

@@ -11,6 +11,7 @@ Unreleased: mitmproxy next
 * Addon to suppress unwanted error messages sent by mitmproxy. (@anneborcherding)
 * Updated imports and styles for web scanner helper addons. (@anneborcherding)
 * Inform when underscore-formatted options are used in client arg. (@jrblixt)
+* ASGIApp should ignore the HTTP flows loaded from somewhere. (@linw1995)
 * Binaries are now built with Python 3.9 (@mhils)
 * Fixed the web UI showing blank page on clicking details tab when server address is missing (@samhita-sopho)
 

mitmproxy/addons/asgiapp.py

@@ -3,8 +3,8 @@ import urllib.parse
 
 import asgiref.compatibility
 import asgiref.wsgi
-
 from mitmproxy import ctx, http
+from mitmproxy.controller import DummyReply
 
 
 class ASGIApp:
@@ -24,9 +24,17 @@ class ASGIApp:
     def name(self) -> str:
         return f"asgiapp:{self.host}:{self.port}"
 
+    def should_serve(self, flow: http.HTTPFlow) -> bool:
+        assert flow.reply
+        return bool(
+            (flow.request.pretty_host, flow.request.port) == (self.host, self.port)
+            and not flow.reply.has_message
+            and not isinstance(flow.reply, DummyReply)  # ignore the HTTP flows of this app loaded from somewhere
+        )
+
     def request(self, flow: http.HTTPFlow) -> None:
         assert flow.reply
-        if (flow.request.pretty_host, flow.request.port) == (self.host, self.port) and not flow.reply.has_message:
+        if self.should_serve(flow):
             flow.reply.take()  # pause hook completion
             asyncio.ensure_future(serve(self.asgi_app, flow))
 

test/mitmproxy/addons/test_asgiapp.py

@@ -1,10 +1,15 @@
+import asyncio
 import json
+import sys
+from unittest import mock
 
 import flask
+import pytest
 from flask import request
 
 from .. import tservers
 from mitmproxy.addons import asgiapp
+from mitmproxy.test import tflow
 
 tapp = flask.Flask(__name__)
 
@@ -68,3 +73,12 @@ class TestApp(tservers.HTTPProxyTest):
             ret = p.request("get:'http://noresponseapp/'")
         assert ret.status_code == 500
         assert b"ASGI Error" in ret.content
+
+    @pytest.mark.skipif(sys.version_info < (3, 8), reason='requires Python 3.8 or higher')
+    def test_app_not_serve_loading_flows(self):
+        with mock.patch('mitmproxy.addons.asgiapp.serve') as mck:
+            flow = tflow.tflow()
+            flow.request.host = "testapp"
+            flow.request.port = 80
+            asyncio.run_coroutine_threadsafe(self.master.load_flow(flow), self.master.channel.loop).result()
+            mck.assert_not_awaited()