k5_size_principal
k5_size_principal(krb5_principal principal, size_t *sizep);
kret = k5_size_principal(ctx->here->princ, &required);
kret = k5_size_principal(ctx->there->princ, &required);
kret = k5_size_principal(authenticator->client, &required);
if (!k5_size_principal(principal, &required) && required <= remain) {
check(k5_size_principal(princ, &elen));
check(k5_size_principal(princ2, &elen2));