k5_externalize_principal
k5_externalize_principal(krb5_principal principal,
kret = k5_externalize_principal(ctx->here->princ,
kret = k5_externalize_principal(ctx->there->princ,
kret = k5_externalize_principal(authenticator->client,
check(k5_externalize_principal(princ, &bp, &blen));
check(k5_externalize_principal(princ2, &bp, &blen));