middleware: Do not consume StreamingHttpResponse.streaming_content.

streaming_content is an iterator. Consuming it within middleware
prevents it from being sent to the browser.

https://docs.djangoproject.com/en/4.2/ref/request-response/#streaminghttpresponse-objects

“The StreamingHttpResponse … has no content attribute. Instead, it has
a streaming_content attribute. This can be used in middleware to wrap
the response iterable, but should not be consumed.”

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/middleware.py

@@ -3,13 +3,13 @@ import logging
 import tempfile
 import time
 import traceback
-from typing import Any, AnyStr, Callable, Dict, Iterable, List, MutableMapping, Optional, Tuple
+from typing import Any, Callable, Dict, List, MutableMapping, Optional, Tuple
 from urllib.parse import urlencode, urljoin
 
 from django.conf import settings
 from django.conf.urls.i18n import is_language_prefix_patterns_used
 from django.db import connection
-from django.http import HttpRequest, HttpResponse, HttpResponseRedirect, StreamingHttpResponse
+from django.http import HttpRequest, HttpResponse, HttpResponseRedirect
 from django.http.response import HttpResponseBase
 from django.middleware.locale import LocaleMiddleware as DjangoLocaleMiddleware
 from django.shortcuts import render
@@ -128,13 +128,8 @@ def write_log_line(
     client_name: str,
     client_version: Optional[str] = None,
     status_code: int = 200,
-    error_content: Optional[AnyStr] = None,
+    error_content: Optional[bytes] = None,
-    error_content_iter: Optional[Iterable[AnyStr]] = None,
 ) -> None:
-    assert error_content is None or error_content_iter is None
-    if error_content is not None:
-        error_content_iter = (error_content,)
-
     time_delta = -1
     # A time duration of -1 means the StartLogRequests middleware
     # didn't run for some reason
@@ -225,14 +220,7 @@ def write_log_line(
 
     # Log some additional data whenever we return certain 40x errors
     if 400 <= status_code < 500 and status_code not in [401, 404, 405]:
-        assert error_content_iter is not None
+        error_data = repr(error_content)
-        error_content_list = list(error_content_iter)
-        if not error_content_list:
-            error_data = ""
-        elif isinstance(error_content_list[0], str):
-            error_data = "".join(error_content_list)
-        elif isinstance(error_content_list[0], bytes):
-            error_data = repr(b"".join(error_content_list))
         if len(error_data) > 200:
             error_data = "[content more than 200 characters]"
         logger.info("status=%3d, data=%s, uid=%s", status_code, error_data, requestor_for_logs)
@@ -360,9 +348,6 @@ class LogRequests(MiddlewareMixin):
             else:
                 requestor_for_logs = "unauth@{}".format(get_subdomain(request) or "root")
 
-        content_iter = (
-            response.streaming_content if isinstance(response, StreamingHttpResponse) else None
-        )
         content = response.content if isinstance(response, HttpResponse) else None
 
         assert request_notes.client_name is not None and request_notes.log_data is not None
@@ -377,7 +362,6 @@ class LogRequests(MiddlewareMixin):
             client_version=request_notes.client_version,
             status_code=response.status_code,
             error_content=content,
-            error_content_iter=content_iter,
         )
         return response