Add name_lookup function in object_ops.

diff --git a/server/sock.c b/server/sock.c
index 0a9b4225..601dd77 100644
--- a/server/sock.c
+++ b/server/sock.c
@@ -108,6 +108,7 @@
     no_satisfied,                 /* satisfied */
     no_signal,                    /* signal */
     sock_get_fd,                  /* get_fd */
+    no_lookup_name,               /* lookup_name */
     no_close_handle,              /* close_handle */
     sock_destroy                  /* destroy */
 };