From: Jeremy Cline <jeremycline@linux.microsoft.com>
Date: Sun, 15 Jun 2025 05:34:29 +0000 (-0400)
Subject: gh-127319: Disable port reuse on HTTP, XMLRPC, and logging TCP servers (GH-135405)
X-Git-Tag: v3.15.0a1~1299
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2bd3895fcabb2dfdae5c0c72e60483e3d3267f0f;p=thirdparty%2FPython%2Fcpython.git

gh-127319: Disable port reuse on HTTP, XMLRPC, and logging TCP servers (GH-135405)

Prior to issue #120485 these servers did not allow port reuse, which
makes sense as the behavior of port reuse is surprising if you're not
expecting it. It's unclear to me why these services were switched to
allow port reuse, but I believe the desired behavior (unless subclasses
opt in) is to not allow port reuse.

See also: https://bugzilla.redhat.com/show_bug.cgi?id=2323170
---

diff --git a/Lib/http/server.py b/Lib/http/server.py
index ef10d1859326..a2ffbe2e44df 100644
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -115,7 +115,7 @@ DEFAULT_ERROR_CONTENT_TYPE = "text/html;charset=utf-8"
 class HTTPServer(socketserver.TCPServer):
 
     allow_reuse_address = True    # Seems to make sense in testing environment
-    allow_reuse_port = True
+    allow_reuse_port = False
 
     def server_bind(self):
         """Override server_bind to store the server name."""
diff --git a/Lib/logging/config.py b/Lib/logging/config.py
index c994349fd6ee..3d9aa00fa52d 100644
--- a/Lib/logging/config.py
+++ b/Lib/logging/config.py
@@ -1018,7 +1018,7 @@ def listen(port=DEFAULT_LOGGING_CONFIG_PORT, verify=None):
         """
 
         allow_reuse_address = True
-        allow_reuse_port = True
+        allow_reuse_port = False
 
         def __init__(self, host='localhost', port=DEFAULT_LOGGING_CONFIG_PORT,
                      handler=None, ready=None, verify=None):
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index fa5b1e438168..e672dfcbb465 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -1036,7 +1036,7 @@ class TestTCPServer(ControlMixin, ThreadingTCPServer):
     """
 
     allow_reuse_address = True
-    allow_reuse_port = True
+    allow_reuse_port = False
 
     def __init__(self, addr, handler, poll_interval=0.5,
                  bind_and_activate=True):
diff --git a/Lib/xmlrpc/server.py b/Lib/xmlrpc/server.py
index 90a356fbb8ea..8130c739af2f 100644
--- a/Lib/xmlrpc/server.py
+++ b/Lib/xmlrpc/server.py
@@ -578,7 +578,7 @@ class SimpleXMLRPCServer(socketserver.TCPServer,
     """
 
     allow_reuse_address = True
-    allow_reuse_port = True
+    allow_reuse_port = False
 
     # Warning: this is for debugging purposes only! Never set this to True in
     # production code, as will be sending out sensitive information (exception
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-06-11-15-08-10.gh-issue-127319.OVGFSZ.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-11-15-08-10.gh-issue-127319.OVGFSZ.rst
new file mode 100644
index 000000000000..d90153c96841
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-11-15-08-10.gh-issue-127319.OVGFSZ.rst
@@ -0,0 +1,3 @@
+Set the ``allow_reuse_port`` class variable to ``False`` on the XMLRPC,
+logging, and HTTP servers. This matches the behavior in prior Python
+releases, which is to not allow port reuse.