OK, here it is - irdp support. But don't expect me to fix any bugs in it.
diff --git a/zebra/interface.c b/zebra/interface.c
index 748bf00..3a7a591 100644
--- a/zebra/interface.c
+++ b/zebra/interface.c
@@ -39,6 +39,7 @@
 #include "zebra/zserv.h"
 #include "zebra/redistribute.h"
 #include "zebra/debug.h"
+#include "zebra/irdp.h"
 
 /* Allocate a new internal interface index 
  * This works done from the top so that %d macros
@@ -1419,6 +1420,10 @@
       rtadv_config_write (vty, ifp);
 #endif /* RTADV */
 
+#ifdef HAVE_IRDP
+      irdp_config_write (vty, ifp);
+#endif /* IRDP */
+
       vty_out (vty, "!%s", VTY_NEWLINE);
     }
   return 0;