Programmer error! Bad Admin server handle

[John Hascall]

What version of Kerberos libraries are you using?

They changed the API for all the kadm5_init* functions
somewhere around 1.6 to add a parameter:

kadm5_ret_t    kadm5_init_with_password(char *client_name,
                                        char *pass,
                                        char *service_name,
                                        kadm5_config_params *params,
                                        krb5_ui_4 struct_version,
                                        krb5_ui_4 api_version,
   /* Heh, look at me, I'm new ----> */ char **db_args,
                                        void **server_handle);

Which has bit me more than once.




> Hello,
> 
> for a project that is mainly developed in Python/Zope, I need to wrap
> some functions of the kadm5-clnt lib. In particular, I need
> 
> kadm5_create_principal
> kadm5_delete_principal
> kadm5_chpass_principal
> 
> to be wrapped into a Python extension. Unfortunately, I'm not very
> familiar with C, so I'm a bit lost here.
> So far I checked out the PyKerberos extension from Apple's
> Calenderserver project and extended it by a kadm5 module, which
> basically consists of the following code (I use the
> kadm5_get_principals method for testing to avoid potentially dangerous
> writes to our Kerberos DB):
> 
> --- snip ---
> #include <Python.h>
> 
> #include <sys/stat.h>
> #include <sys/types.h>
> #include <com_err.h>
> 
> #include <krb5.h>
> 
> #include "admin.h"
> 
> 
> static PyObject *k5_error;
> 
> #define RETURN_ON_ERROR(message, code) \
>   do if (code != 0) \
>   { \
>     const char *error; \
>     error = krb5_get_error_message(ctx, code); \
>     PyErr_Format(k5_error, "%s: %s", message, error); \
>     krb5_free_error_message(ctx, error); \
>     return NULL; \
>   } while (0)
> 
> 
> 
> static PyObject *getPrincipals(PyObject *self, PyObject *args)
> {
>     char *client;
>     char *pass;
>     char *realm;
>     void **handle;
>     char ***princs;
>     int *count;
>     krb5_context ctx;
>     krb5_error_code code = 0;
> 
>     code = krb5_init_context(&ctx);
>     RETURN_ON_ERROR("krb5_init_context()", code);
> 
>     if (!PyArg_ParseTuple(args, "sss", &client, &pass, &realm))
>       return NULL;
> 
>     code = kadm5_init_with_password(client, pass, KADM5_ADMIN_SERVICE,
>                 realm, KADM5_STRUCT_VERSION_1, KADM5_API_VERSION_1,
>                 handle);
>     RETURN_ON_ERROR("kadm5_init_with_password()", code);
> 
>     code = kadm5_get_principals(&handle, "*", princs, count);
>     RETURN_ON_ERROR("kadm5_get_principals()", code);
> 
> /*    return Py_BuildValue("s", &princs); */
>     return Py_BuildValue("");
> }
> 
> 
> static PyMethodDef kadm5Methods[] = {
>     {"kadm5_get_principals", getPrincipals, METH_VARARGS, "Test."},
>     {NULL, NULL, 0, NULL}        /* Sentinel */
> };
> 
> PyMODINIT_FUNC initkadm5(void)
> {
>     PyObject *module, *dict;
> 
>     initialize_krb5_error_table();
> 
>     module = Py_InitModule("kadm5", kadm5Methods);
>     dict = PyModule_GetDict(module);
>     k5_error = PyErr_NewException("PyKerberos.kadm5.Error", NULL, NULL);
>     PyDict_SetItemString(dict, "Error", k5_error);
> }
> --- snap ---
> 
> If you ignore the Python wrapping stuff, you'll see that the code
> consecutively calls kadm5_init_with_password and kadm5_get_principals,
> where the latter doesn't accept the server-handle referenced by the
> first.
> kadm5_init_with_password returns "correct" errors, if I provide an
> unconfigured realm or a wrong client_name/password combination, so
> that's not it.
> I don't know, if I did all the (de)referencing for the handle right or
> if I have some fundamental misunderstanding here.
> Does someone have a clue what's wrong?
> 
> Thank you in advance and best regards,
> Torsten
> -- 
>   Gentlemen, I want you to know that I am not always right, but I am
>   never wrong. -Samuel Goldwyn
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