safety check

diff --git a/src/transport/gnunet-service-transport.c b/src/transport/gnunet-service-transport.c
index 0bb19a9cf27a0cb9585f0e38cff0a56ba7d7e52a..b2fa62d0de6e94f2f5714ad770889c4a9d578585 100644 (file)
--- a/src/transport/gnunet-service-transport.c
+++ b/src/transport/gnunet-service-transport.c
@@ -4516,9 +4516,10 @@ handle_ping(void *cls, const struct GNUNET_MessageHeader *message,
       memcpy (&pong[1],
              plugin->short_name,
              slen);
-      memcpy (&((char*)&pong[1])[slen],
-             sender_address,
-             sender_address_len);
+      if ((sender_address!=NULL) && (sender_address_len > 0))
+                 memcpy (&((char*)&pong[1])[slen],
+                         sender_address,
+                         sender_address_len);
       if (GNUNET_TIME_absolute_get_remaining (session_header->pong_sig_expires).rel_value < PONG_SIGNATURE_LIFETIME.rel_value / 4)
        {
          /* create / update cached sig */