Issue #10883: Fix socket leaks in urllib.request.

* ftpwrapper now uses reference counting to ensure that the underlying socket
  is closed when the ftpwrapper object is no longer in use
* ftplib.FTP.ntransfercmd() now closes the socket if an error occurs

Initial patch by Victor Stinner.

1 files changed, 8 insertions, 1 deletions

diff --git a/Lib/urllib2.py b/Lib/urllib2.py
index 26416193f6..2bce745e63 100644
--- a/Lib/urllib2.py
+++ b/Lib/urllib2.py
@@ -1399,7 +1399,8 @@ class FTPHandler(BaseHandler):
             raise URLError, ('ftp error: %s' % msg), sys.exc_info()[2]
 
     def connect_ftp(self, user, passwd, host, port, dirs, timeout):
-        fw = ftpwrapper(user, passwd, host, port, dirs, timeout)
+        fw = ftpwrapper(user, passwd, host, port, dirs, timeout,
+                        persistent=False)
 ##        fw.ftp.set_debuglevel(1)
         return fw
 
@@ -1448,3 +1449,9 @@ class CacheFTPHandler(FTPHandler):
                     del self.timeout[k]
                     break
             self.soonest = min(self.timeout.values())
+
+    def clear_cache(self):
+        for conn in self.cache.values():
+            conn.close()
+        self.cache.clear()
+        self.timeout.clear()