proxy: fix active open connection cleanup

Thanks to DucTM for spotting the issue.

Change-Id: I7985560f224c99cf0fdeea0c8457a3ac6f10b03c
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/session-apps/proxy.c b/src/vnet/session-apps/proxy.c
index 58412e0..596b037 100644
--- a/src/vnet/session-apps/proxy.c
+++ b/src/vnet/session-apps/proxy.c
@@ -105,9 +105,9 @@
       else if (!pool_is_free_index (pm->sessions, p[0]))
 	{
 	  ps = pool_elt_at_index (pm->sessions, p[0]);
-	  if (ps->vpp_server_handle != ~0)
+	  if (ps->vpp_active_open_handle != ~0)
 	    active_open_session = session_get_from_handle
-	      (ps->vpp_server_handle);
+	      (ps->vpp_active_open_handle);
 	  else
 	    active_open_session = 0;
 	}