len_string
CHECK(krb5_store_uint16(out, len_string(ucs2, s)), 0);
domain.length = len_string(0, type1->domain);
hostname.length = len_string(0, type1->hostname);
targetname.length = len_string(ucs2, type2->targetname);
target.length = len_string(ucs2, type3->targetname);
username.length = len_string(ucs2, type3->username);
ws.length = len_string(ucs2, type3->ws);