From 3d37ea25dc97e4cb024045581979570835deb13c Mon Sep 17 00:00:00 2001
From: Petter Strandmark <petter.strandmark@gmail.com>
Date: Wed, 1 May 2019 19:32:15 +0200
Subject: [PATCH] bpo-27682: Handle client connection terminations in wsgiref
 (GH-9713)

---
 Lib/test/test_wsgiref.py                       | 18 ++++++++++++++++++
 Lib/wsgiref/handlers.py                        |  4 ++++
 .../2018-10-05-16-01-00.bpo-34547.abbaa.rst    |  2 ++
 3 files changed, 24 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2018-10-05-16-01-00.bpo-34547.abbaa.rst

diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index 737dfed3a51..46f88a94434 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -788,6 +788,24 @@ class HandlerTests(TestCase):
             b"Hello, world!",
             written)
 
+    def testClientConnectionTerminations(self):
+        environ = {"SERVER_PROTOCOL": "HTTP/1.0"}
+        for exception in (
+            ConnectionAbortedError,
+            BrokenPipeError,
+            ConnectionResetError,
+        ):
+            with self.subTest(exception=exception):
+                class AbortingWriter:
+                    def write(self, b):
+                        raise exception
+
+                stderr = StringIO()
+                h = SimpleHandler(BytesIO(), AbortingWriter(), stderr, environ)
+                h.run(hello_app)
+
+                self.assertFalse(stderr.getvalue())
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/wsgiref/handlers.py b/Lib/wsgiref/handlers.py
index 28ed9b7a6d0..834073d5009 100644
--- a/Lib/wsgiref/handlers.py
+++ b/Lib/wsgiref/handlers.py
@@ -136,6 +136,10 @@ class BaseHandler:
             self.setup_environ()
             self.result = application(self.environ, self.start_response)
             self.finish_response()
+        except (ConnectionAbortedError, BrokenPipeError, ConnectionResetError):
+            # We expect the client to close the connection abruptly from time
+            # to time.
+            return
         except:
             try:
                 self.handle_error()
diff --git a/Misc/NEWS.d/next/Library/2018-10-05-16-01-00.bpo-34547.abbaa.rst b/Misc/NEWS.d/next/Library/2018-10-05-16-01-00.bpo-34547.abbaa.rst
new file mode 100644
index 00000000000..7b63c05ed2b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-10-05-16-01-00.bpo-34547.abbaa.rst
@@ -0,0 +1,2 @@
+:class:`wsgiref.handlers.BaseHandler` now handles abrupt client connection
+terminations gracefully. Patch by Petter Strandmark.