Problems in LDAPControl handling

[Salvador Ortiz Garcia <sog@msg.com.mx>]

Hello all.

My name is Salvador and this is my first post to the list. 

I know that the C API documentation in the 2.x series its incomplete, so
for my proyect I'm using both the (expired) c-api draft and the sources as
a reference.

While reading controls.c I found what IMHO is a bug in ldap_create_control
and a potential problem in ldap_control_dup (both undocumented yet but
very useful):

First the bug:

ldap_control_create returns LDAP_PARAM_ERROR when ber == NULL, a
BUG in my opinion because it is perfectly valid to create a control
without a controlValue.

BTW, ldap_control_create depends on ber_flatten that allows ber==NULL, so
I suggest:

-        if ( requestOID == NULL || ber == NULL || ctrlp == NULL ) {
+        if ( requestOID == NULL || ctrlp == NULL ) {

Now the problem:

In the draft, in 11.3 "Working With Controls" i can read:

   ldctl_value      The data associated with the control (if any).  To
                    specify a zero-length value, set ldctl_value.bv_len to
                    zero and ldctl_value.bv_val to a zero-length string.
                    To indicate that no data is associated with the con-
                    trol, set ldctl_value.bv_val to NULL.

So we have two diferent cases with bv_len == 0, that makes sense to 
me because in the ASN1 a controlValue is defined as OCTECT STRING OPTIONAL
so 

'bv_len == 0, bv_val == NULL' eq "no controlValue" 

and

'bv_len == 0, bv_val == ""' supplies a empty but existent controlValue.

But in ldap_control_dup i read:

        if( c->ldctl_value.bv_len > 0 ) {
                ...
        } else {
                new->ldctl_value.bv_len = 0;
                new->ldctl_value.bv_val = NULL;
        }

That turns a control with a "zero length" controlValue into a control
without it.

As commented above, ldap_control_create uses ber_flatten to initialize a
new control and ber_flatten with ber == NULL creates an empty berval
(bv_len == 0, bv_val == NULL) but with ber != NULL it allocates memory
(one byte, for the char(\0)) even in the case len == 0.

I don't know if in reallity can be a ldap control with diferent
semantics for the two cases, so I'm asking you for some expert advise.

Best Regards, and please forgive my poor English.

Salvador Ortiz