bpo-30329: Catch Windows error 10022 on shutdown() (#1538)

Catch the Windows socket WSAEINVAL error (code 10022) in imaplib and
poplib on shutdown(SHUT_RDWR): An invalid operation was attempted

This error occurs sometimes on SSL connections.

1 files changed, 6 insertions, 3 deletions

diff --git a/Lib/imaplib.py b/Lib/imaplib.py
index 2fa9012..1c0b03b 100644
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -318,9 +318,12 @@ class IMAP4:
         self.file.close()
         try:
             self.sock.shutdown(socket.SHUT_RDWR)
-        except OSError as e:
-            # The server might already have closed the connection
-            if e.errno != errno.ENOTCONN:
+        except OSError as exc:
+            # The server might already have closed the connection.
+            # On Windows, this may result in WSAEINVAL (error 10022):
+            # An invalid operation was attempted.
+            if (exc.errno != errno.ENOTCONN
+               and getattr(exc, 'winerror', 0) != 10022):
                 raise
         finally:
             self.sock.close()