Fix logging of client addresses with IPv6 scope (#2953)

CHANGES.rst

@@ -6,6 +6,7 @@ Version 3.0.5
 Unreleased
 
 -   The Watchdog reloader ignores file closed no write events. :issue:`2945`
+-   Logging works with client addresses containing an IPv6 scope :issue:`2952`
 
 
 Version 3.0.4

src/werkzeug/serving.py

@@ -473,9 +473,11 @@ def log_message(self, format: str, *args: t.Any) -> None:
         self.log("info", format, *args)
 
     def log(self, type: str, message: str, *args: t.Any) -> None:
+        # an IPv6 scoped address contains "%" which breaks logging
+        address_string = self.address_string().replace("%", "%%")
         _log(
             type,
-            f"{self.address_string()} - - [{self.log_date_time_string()}] {message}\n",
+            f"{address_string} - - [{self.log_date_time_string()}] {message}\n",
             *args,
         )
 

tests/live_apps/run.py

@@ -4,6 +4,7 @@
 
 from werkzeug.serving import generate_adhoc_ssl_context
 from werkzeug.serving import run_simple
+from werkzeug.serving import WSGIRequestHandler
 from werkzeug.wrappers import Request
 from werkzeug.wrappers import Response
 
@@ -23,10 +24,14 @@ def app(request):
 kwargs.update(hostname="127.0.0.1", port=5000, application=app)
 kwargs.update(json.loads(sys.argv[2]))
 ssl_context = kwargs.get("ssl_context")
+override_client_addr = kwargs.pop("override_client_addr", None)
 
 if ssl_context == "custom":
     kwargs["ssl_context"] = generate_adhoc_ssl_context()
 elif isinstance(ssl_context, list):
     kwargs["ssl_context"] = tuple(ssl_context)
 
+if override_client_addr:
+    WSGIRequestHandler.address_string = lambda _: override_client_addr
+
 run_simple(**kwargs)

tests/test_serving.py

@@ -337,3 +337,14 @@ def test_streaming_chunked_truncation(dev_server):
     """
     with pytest.raises(http.client.IncompleteRead):
         dev_server("streaming", threaded=True).request("/crash")
+
+
+@pytest.mark.filterwarnings("ignore::pytest.PytestUnraisableExceptionWarning")
+@pytest.mark.dev_server
+def test_host_with_ipv6_scope(dev_server):
+    client = dev_server(override_client_addr="fe80::1ff:fe23:4567:890a%eth2")
+    r = client.request("/crash")
+
+    assert r.status == 500
+    assert b"Internal Server Error" in r.data
+    assert "Logging error" not in client.log.read()