gettdb_dir
struct tdb *gettdb_dir(u_int, u_int32_t, union sockaddr_union *, u_int8_t, int);
#define gettdb(a,b,c,d) gettdb_dir((a),(b),(c),(d),0)
#define gettdb_rev(a,b,c,d) gettdb_dir((a),(b),(c),(d),1)