python: Don't raise an Exception on failure to connect via SSL.

With other socket types, trying to connect and failing will return
an error code, but if an SSL Stream is used, then when
check_connection_completion(sock) is called, SSL will raise an
exception that doesn't derive from socket.error which is handled.

This adds handling for SSL.SysCallError which has the same
arguments as socket.error (errno, string). A future enhancement
could be to go through SSLStream class and implement error
checking for all of the possible exceptions similar to how
lib/stream-ssl.c's interpret_ssl_error() works across the various
methods that are implemented.

Fixes: d90ed7d ("python: Add SSL support to the python ovs client library")
Signed-off-by: Terry Wilson <twilson@redhat.com>
Acked-by: Thomas Neuman <thomas.neuman@nutanix.com>
Acked-by: Mark Michelson <mmichels@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

python/ovs/stream.py

@@ -134,6 +134,10 @@ def __init__(self, socket, name, status, pipe=None, is_server=False):
     IPTOS_PREC_INTERNETCONTROL = 0xc0
     DSCP_DEFAULT = IPTOS_PREC_INTERNETCONTROL >> 2
 
+    @staticmethod
+    def check_connection_completion(sock):
+        return ovs.socket_util.check_connection_completion(sock)
+
     @staticmethod
     def open(name, dscp=DSCP_DEFAULT):
         """Attempts to connect a stream to a remote peer.  'name' is a
@@ -191,7 +195,7 @@ def open(name, dscp=DSCP_DEFAULT):
         if error:
             return error, None
         else:
-            err = ovs.socket_util.check_connection_completion(sock)
+            err = cls.check_connection_completion(sock)
             if err == errno.EAGAIN or err == errno.EINPROGRESS:
                 status = errno.EAGAIN
                 err = 0
@@ -253,7 +257,7 @@ def close(self):
 
     def __scs_connecting(self):
         if self.socket is not None:
-            retval = ovs.socket_util.check_connection_completion(self.socket)
+            retval = self.check_connection_completion(self.socket)
             assert retval != errno.EINPROGRESS
         elif sys.platform == 'win32':
             if self.retry_connect:
@@ -753,6 +757,13 @@ def _open(suffix, dscp):
 
 
 class SSLStream(Stream):
+    @staticmethod
+    def check_connection_completion(sock):
+        try:
+            return Stream.check_connection_completion(sock)
+        except SSL.SysCallError as e:
+            return ovs.socket_util.get_exception_errno(e)
+
     @staticmethod
     def needs_probes():
         return True