[389-devel] Please review: Plugin Default Config Entry

[Rich Megginson]

Noriko Hosoi wrote:
> Plugin Default Config Entry
>
> Design doc:
> http://directory.fedoraproject.org/wiki/Entry_USN#Plugin_Default_Config_Entry 
>
>
> New slapi APIs in libslapd:
>   int slapi_set_plugin_default_config(char *type, char *attr);
>   Description: Set given "type: attr" to the plugin default config entry
>                (cn=plugin default config,cn=config).
>   Parameters: type - Attribute type to add to the default config entry
>               attr - Attribute value to add to the default config entry
>   Return Value: 0 if the operation was successful
>                 non-0 if the operation was not successful
>
>   int slapi_get_plugin_default_config(char *type, char ***attrs);
>   Description: Get attribute values of given type from the plugin default
>                config entry (cn=plugin default config,cn=config).
>   Parameters: type - Attribute type to get from the default config entry
>               attrs - Pointer to the string array to store the values of
>                       the attribute
>   Return Value: 0 if the operation was successful
>               non-0 if the operation was not successful
>   warning: Caller is responsible to free attrs by slapi_ch_array_free
>
> Changes in the Replication plugin:
> 1) Functions to set replicated attributes
>        agmt_set_replicated_attributes_from_attr and
>        agmt_set_replicated_attributes_from_entry
>    call _agmt_set_default_fractional_attrs to sets the default excluded
>    attribute list from the plugin default config entry before setting
>    them from each replication agreement.
>    To support it, agmt_parse_excluded_attrs_config_attr is changed to be
>    re-entrant.
> 2) Fixed a minor memory leak in the fractional attributes 
> (ra->frac_attrs).
> 3) Added a check for the duplicated fractional attributes.
>
> Changes in the USN plugin:
> usn_start calls slapi_get_plugin_default_config to check if "entryusn" is
> in the EXCLUDE list of the value of nsds5ReplicatedAttributeList in the
> plugin default config entry or not.  If it does not exist, the function
> adds it.  Note: If the nsds5ReplicatedAttributeList value exists and
> "entryusn" is not in the EXCLUDE list, we have to append it to the list
> instead of replacing it.
>
> Thanks,
> --noriko
> ------------------------------------------------------------------------
>
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> 389-devel at redhat.com
> https://www.redhat.com/mailman/listinfo/fedora-directory-devel
About this code:
     if (new_attrs)
     {
-        *attrs = new_attrs;
+        charray_merge_nodup(attrs, new_attrs, 0);
+        slapi_ch_free((void **)&new_attrs);
     }

the 0 flag to charray_merge_nodup() means "do not copy" - so the strings 
in new_attrs will be moved to attrs, if they are not duplicates.  If 
they are duplicates, they will not be moved - how will they be freed?  
There's no way for the caller of charray_merge_nodup to know which 
strings were moved and which were not (except by comparing pointers in 
attrs with new_attrs).

+            int i;
+            const char *val = slapi_value_get_string(sval);
+            for (i = slapi_attr_first_value(attr, &sval);

I don't think you should be calling slapi_value_get_string() here since 
sval is not initialized yet.

I think slapi_set_plugin_default_config() should always to a modify/add, 
and just ignore "type or value exists" errors.  Or support single valued 
attributes only.  Or allow the user to specify to add or replace in the 
case of a multi-valued attribute. What if the user modifies the list 
directly over LDAP or by editing dse.ldif?  An internal call to set the 
value will wipe out their settings.  Also, there is a reference to 
frational attr in the slapi_set_plugin_default_config() code.

I think slapi_set_plugin_default_config() will leak the pblock used for 
the initial search if rc != LDAP_SUCCESS or entries is NULL or empty.

slapi_get_plugin_default_config() - since you are assuming that the 
values of the requested attribute are all null terminated strings (since 
you are using slapi_value_get_string()), you could just use 
slapi_entry_attr_get_charray() to get all of the values as a char **.

Why does slapi_set_plugin_default_config() take a char * argument i.e. 
setting an attribute with a single string value, but 
slapi_get_plugin_default_config() returns multiple values from a single 
attribute?

I'm not sure what the code in usn_start() is doing.  Is 
nsds5ReplicatedAttributeList multi-valued?  If so, each char * in char 
**old_frac_attrs will be a full attribute list description 
"(objectclass=*) $ EXCLUDE ...".  Then I'm not sure what the code that 
adds the entryusn attribute to the default excluded list is doing - will 
it add entryusn to only the first value of 
nsds5ReplicatedAttributeList?  And wipe out the other values?  I think 
that's what will happen, since there is a break in the for loop if token 
== NULL - it will skip old_frac_attrs[1] etc.  Also the call to 
charray_add - the token argument is not a malloced string, so that will 
cause problems when slapi_ch_array_free() is called.

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