Document revision date: 30 March 2001

## OpenVMS Utility Routines Manual

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## 12.8 Closing the Session

The following functions are used to unbind from the directory, close the connection, and dispose of the session handle.

            int ldap_unbind( LDAP *ld );
            int ldap_unbind_s( LDAP *ld );

Parameter is as follows:

ld | The session handle.

The `ldap_unbind()` and `ldap_unbind_s()` functions both work synchronously, unbinding from the directory, closing the connection, and freeing up the ld structure before returning. There is no server response to an unbind operation. The `ldap_unbind()` function returns LDAP_SUCCESS (or another LDAP error code if the request cannot be sent to the LDAP server). After a call to `ldap_unbind()` or `ldap_unbind_s()` , the session handle ld is invalid and it is illegal to make any further LDAP API calls using ld.

## 12.9 Searching

The following functions are used to search the LDAP directory, returning a requested set of attributes for each entry matched. There are five variations.

            int ldap_search_ext(
                    LDAP                      *ld,
                    const char                *base,
                    int                       scope,
                    const char                *filter,
                    char                      **attrs,
                    int                       attrsonly,
                    LDAPControl               **serverctrls,
                    LDAPControl               **clientctrls,
                    struct timeval            *timeout,
                    int                       sizelimit,
                    int                       *msgidp
            );

            int ldap_search_ext_s(
                    LDAP                      *ld,
                    const char                *base,
                    int                       scope,
                    const char                *filter,
                    char                      **attrs,
                    int                       attrsonly,
                    LDAPControl               **serverctrls,
                    LDAPControl               **clientctrls,
                    struct timeval            *timeout,
                    int                       sizelimit,
                    LDAPMessage               **res
            );

            int ldap_search(
                    LDAP                      *ld,
                    const char                *base,
                    int                       scope,
                    const char                *filter,
                    char                      **attrs,
                    int                       attrsonly
            );

            int ldap_search_s(
                    LDAP                      *ld,
                    const char                *base,
                    int                       scope,
                    const char                *filter,
                    char                      **attrs,
                    int                       attrsonly,
                    LDAPMessage               **res
            );

            int ldap_search_st(
                    LDAP                      *ld,
                    char                      *base,
                    int                       scope,
                    char                      *filter,
                    char                      **attrs,
                    int                       attrsonly,
                    struct timeval            *timeout,
                    LDAPMessage               **res
               );

Parameters are as follows:

ld | The session handle.
base | The dn of the entry at which to start the search.
scope | One of LDAP_SCOPE_BASE (0x00), LDAP_SCOPE_ONELEVEL (0x01), or LDAP_SCOPE_SUBTREE (0x02), indicating the scope of the search.
filter | A character string representing the search filter. The value NULL can be passed to indicate that the filter (objectclass=*) that matches all entries should be used.
attrs | A NULL-terminated array of strings indicating which attributes to return for each matching entry. Passing NULL for this parameter causes all available user attributes to be retrieved. The special constant string LDAP_NO_ATTRS (1.1) can be used as the only element in the array to indicate that no attribute types should be returned by the server. The special constant string LDAP_ALL_USER_ATTRS (*), can be used in the attrs array along with the names of some operational attributes to indicate that all user attributes plus the listed operational attributes should be returned.
attrsonly | A boolean value that should be either zero if both attribute types and values are to be returned or non-zero if only types are wanted.
timeout | For the `ldap_search_st()` function, this specifies the local search timeout value (if it is NULL, the timeout is infinite). For the `ldap_search_ext()` and `ldap_search_ext_s()` functions, this specifies both the local search timeout value and the operation time limit that is sent to the server within the search request. For the `ldap_search_ext()` and `ldap_search_ext_s()` functions, passing a NULL value for timeout causes the global default timeout stored in the LDAP session handle to be used (set using `ldap_set_option()` with the LDAP_OPT_TIMELIMIT parameter).
sizelimit | For the `ldap_search_ext()` and `ldap_search_ext_s()` calls, this is a limit on the number of entries to return from the search. A value of LDAP_NO_LIMIT (0) means no limit.
res | For the synchronous calls, this is a result parameter which will contain the results of the search upon completion of the call.
serverctrls | List of LDAP server controls.
clientctrls | List of client controls.
msgidp | This result parameter will be set to the message id of the request if the `ldap_search_ext()` call succeeds.

There are three options in the session handle ld that potentially affect how the search is performed. They are as follows:

LDAP_OPT_SIZELIMIT | A limit on the number of entries to return from the search. A value of LDAP_NO_LIMIT (0) means no limit. Note that the value from the session handle is ignored when using the `ldap_search_ext()` or `ldap_search_ext_s()` functions.
LDAP_OPT_TIMELIMIT | A limit on the number of seconds to spend on the search. A value of LDAP_NO_LIMIT (0) means no limit. Note that the value from the session handle is ignored when using the `ldap_search_ext()` or `ldap_search_ext_s()` functions.
LDAP_OPT_DEREF | One of LDAP_DEREF_NEVER(0x00), LDAP_DEREF_SEARCHING(0x01), LDAP_DEREF_FINDING (0x02), or LDAP_DEREF_ALWAYS (0x03), specifying how aliases should be handled during the search. The LDAP_DEREF_SEARCHING value means aliases should be dereferenced during the search but not when locating the base object of the search. The LDAP_DEREF_FINDING value means aliases should be dereferenced when locating the base object but not during the search.

The `ldap_search_ext()` function initiates an asynchronous search operation and returns either the constant LDAP_SUCCESS if the request was successfully sent or another LDAP error code if not. See Section 12.18 for more information about possible errors and how to interpret them. If successful, `ldap_search_ext()` places the message id of the request in *msgidp. A subsequent call to `ldap_result()` can be used to obtain the results from the search. These results can be parsed using the result parsing functions described in Section 12.18.

Similar to `ldap_search_ext()` , the `ldap_search()` function initiates an asynchronous search operation and returns the message id of the operation initiated. As for `ldap_search_ext()` , a subsequent call to `ldap_result()` can be used to obtain the result of the bind. In case of error, `ldap_search()` will return -1, setting the session error parameters in the LDAP structure appropriately.

The synchronous `ldap_search_ext_s()` , `ldap_search_s()` , and `ldap_search_st()` functions all return the result of the operation, either the constant LDAP_SUCCESS if the operation was successful or another LDAP error code if it was not. See Section 12.18 for more information about possible errors and how to interpret them. Entries returned from the search (if any) are contained in the res parameter. This parameter is opaque to the caller. Entries, attributes, and values should be extracted by calling the parsing functions. The results contained in res should be freed when no longer in use by calling `ldap_msgfree()` .

The `ldap_search_ext()` and `ldap_search_ext_s()` functions support LDAPv3 server controls, client controls, and allow varying size and time limits to be easily specified for each search operation. The `ldap_search_st()` function is identical to `ldap_search_s()` except that it takes an additional parameter specifying a local timeout for the search. The local search timeout is used to limit the amount of time the API implementation will wait for a search to complete. After the local search timeout the search operation will return LDAP_TIMEOUT if the search result has not been removed.

### 12.9.1 Reading and Listing the Children of an Entry

LDAP does not support a read operation directly. Instead, this operation is emulated by a search with base set to the DN of the entry to read, scope set to LDAP_SCOPE_BASE, and filter set to "(objectclass=*)" or NULL. The attrs parameter contains the list of attributes to return.

LDAP does not support a list operation directly. Instead, this operation is emulated by a search with base set to the DN of the entry to list, scope set to LDAP_SCOPE_ONELEVEL, and filter set to "(objectclass=*)" or NULL. The attrs parameter contains the list of attributes to return for each child entry.

## 12.10 Comparing a Value Against an Entry

The following functions are used to compare a given attribute value assertion against an LDAP entry. There are four variations.

            int ldap_compare_ext(
                    LDAP                              *ld,
                    const char                        *dn,
                    const char                        *attr,
                    const struct berval               *bvalue
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls,
                    int                               *msgidp
            );

            int ldap_compare_ext_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    const char                        *attr,
                    const struct berval               *bvalue,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls
            );

            int ldap_compare(
                    LDAP                              *ld,
                    const char                        *dn,
                    const char                        *attr,
                    const char                        *value
            );

            int ldap_compare_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    const char                        *attr,
                    const char                        *value
            );

Parameters are as follows:

ld | The session handle.
dn | The name of the entry to compare against.
attr | The attribute to compare against.
bvalue | The attribute value to compare against those found in the given entry. This parameter is used in the extended functions and is a pointer to a struct berval so it is possible to compare binary values.
value | A string attribute value to compare against, used by the `ldap_compare()` and `ldap_compare_s()` functions. Use `ldap_compare_ext()` or `ldap_compare_ext_s()` if you need to compare binary values.
serverctrls | List of LDAP server controls.
clientctrls | List of client controls.
msgidp | This result parameter will be set to the message id of the request if the `ldap_compare_ext()` call succeeds. The `ldap_compare_ext()` function initiates an asynchronous compare operation and returns either the constant LDAP_SUCCESS if the request was successfully sent, or another LDAP error code if not. See Section 12.18 for more information about possible errors and how to interpret them. If successful, `ldap_compare_ext()` places the message id of the request in *msgidp. A subsequent call to `ldap_result()` can be used to obtain the result of the compare.

Similar to `ldap_compare_ext()` , the `ldap_compare()` function initiates an asynchronous compare operation and returns the message id of the operation initiated. As for `ldap_compare_ext()` , a subsequent call to `ldap_result()` can be used to obtain the result of the bind. In case of error, `ldap_compare()` will return -1, setting the session error parameters in the LDAP structure appropriately.

The synchronous `ldap_compare_ext_s()` and `ldap_compare_s()` functions both return the result of the operation, either the constants LDAP_COMPARE_TRUE or LDAP_COMPARE_FALSE if the operation was successful, or another LDAP error code if it was not. See Section 12.18 for more information about possible errors and how to interpret them.

The `ldap_compare_ext()` and `ldap_compare_ext_s()` functions support LDAPv3 server controls and client controls.

## 12.11 Modifying an Entry

The following functions are used to modify an existing LDAP entry. There are four variations.

            typedef struct ldapmod {
                    int                                mod_op;
                    char                               *mod_type;
                    union {
                            char                       **modv_strvals;
                            struct berval              **modv_bvals;
                            } mod_vals;
            } LDAPMod;
            #define mod_values      mod_vals.modv_strvals
            #define mod_bvalues     mod_vals.modv_bvals

            int ldap_modify_ext(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls,
                    int                               *msgidp
            );

            int ldap_modify_ext_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls

            );

            int ldap_modify(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods
            );

            int ldap_modify_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods
            );

Parameters are as follows:

ld | The session handle.
dn | The name of the entry to modify.
mods | A NULL-terminated array of modifications to make to the entry.
serverctrls | List of LDAP server controls.
clientctrls | List of client controls.
msgidp | This result parameter will be set to the message id of the request if the `ldap_modify_ext()` call succeeds.

The fields in the LDAPMod structure have the following meanings:

mod_op | The modification operation to perform. It should be one of LDAP_MOD_ADD(0x00), LDAP_MOD_DELETE (0x01), or LDAP_MOD_REPLACE(0x02). This field also indicates the type of values included in the mod_vals union. It is logically ORed with LDAP_MOD_BVALUES (0x80) to select the mod_bvalues form. Otherwise, the mod_values form is used.
mod_type | The type of the attribute to modify.
mod_vals | The values (if any) to add, delete, or replace. Only one of the mod_values or mod_bvalues variants should be used, selected by ORing the mod_op field with the constant LDAP_MOD_BVALUES. The mod_values field is a NULL-terminated array of zero-terminated strings and mod_bvalues is a NULL- terminated array of berval structures that can be used to pass binary values such as images.

For LDAP_MOD_ADD modifications, the given values are added to the entry, creating the attribute if necessary.

For LDAP_MOD_DELETE modifications, the given values are deleted from the entry, removing the attribute if no values remain. If the entire attribute is to be deleted, the mod_vals field should be set to NULL.

For LDAP_MOD_REPLACE modifications, the attribute will have the listed values after the modification, having been created if necessary, or removed if the mod_vals field is NULL. All modifications are performed in the order in which they are listed.

The `ldap_modify_ext()` function initiates an asynchronous modify operation and returns the constant LDAP_SUCCESS if the request was successfully sent, or another LDAP error code if not. See Section 12.18 for more information about possible errors and how to interpret them. If successful, `ldap_modify_ext()` places the message id of the request in *msgidp. A subsequent call to `ldap_result()` can be used to obtain the result of the modify.

Similar to `ldap_modify_ext()` , the `ldap_modify()` function initiates an asynchronous modify operation and returns the message id of the operation initiated. As for `ldap_modify_ext()` , a subsequent call to `ldap_result()` can be used to obtain the result of the modify. In case of error, `ldap_modify()` will return -1, setting the session error parameters in the LDAP structure appropriately.

The synchronous `ldap_modify_ext_s()` and `ldap_modify_s()` functions both return the result of the operation, either the constant LDAP_SUCCESS if the operation was successful, or another LDAP error code if it was not.

See Section 12.18 for more information about possible errors and how to interpret them.

The `ldap_modify_ext()` and `ldap_modify_ext_s()` functions support LDAPv3 server controls and client controls.

## 12.12 Modifying the Name of an Entry

In LDAP Version 2, the `ldap_modrdn()` and `ldap_modrdn_s()` functions were used to change the name of an LDAP entry. They could only be used to change the least significant component of a name (the RDN or relative distinguished name). LDAPv3 provides the Modify DN protocol operation that allows more general name change access. The `ldap_rename()` and `ldap_rename_s()` functions are used to change the name of an entry, and the use of the `ldap_modrdn()` and `ldap_modrdn_s()` functions is deprecated.

            int ldap_rename(
                    LDAP                              *ld,
                    const char                        *dn,
                    const char                        *newrdn,
                    const char                        *newparent,
                    int                               deleteoldrdn,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls,
                    int                               *msgidp
            );

            int ldap_rename_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    const char                        *newrdn,
                    const char                        *newparent,
                    int                               deleteoldrdn,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls
            );

Use of the following functions is deprecated.

            int ldap_modrdn(
                    LDAP                              *ld,
                    char                              *dn,
                    char                              *newrdn,
                    int                               deleteoldrdn
            );

            int ldap_modrdn_s(
                    LDAP                              *ld,
                    char                              *dn,
                    char                              *newrdn,
                    int                               deleteoldrdn
            );

Parameters are as follows:

ld | The session handle.
dn | The name of the entry whose DN is to be changed.
newrdn | The new RDN to give the entry.
newparent | The new parent, or superior entry. If this parameter is NULL, only the RDN of the entry is changed. The root DN may be specified by passing a zero length string, "". The newparent parameter should always be NULL when using Version 2 of the LDAP protocol; otherwise the server's behavior is undefined.
deleteoldrdn | This parameter only has meaning on the rename functions if newrdn is different than the old RDN. It is a boolean value. If it is non-zero, it indicates that the old RDN value(s) should be removed. If it is zero, it indicates that the old RDN value(s) should be retained as non-distinguished values of the entry.
serverctrls | List of LDAP server controls.
clientctrls | List of client controls.
msgidp | This result parameter will be set to the message id of the request if the `ldap_rename()` call succeeds.

The `ldap_rename()` function initiates an asynchronous modify DN operation and returns the constant LDAP_SUCCESS if the request was successfully sent, or another LDAP error code if not. See Section 12.18 for more information about possible errors and how to interpret them. If successful, `ldap_rename()` places the DN message id of the request in *msgidp. A subsequent call to `ldap_result()` can be used to obtain the result of the rename.

The synchronous `ldap_rename_s()` returns the result of the operation, either the constant LDAP_SUCCESS if the operation was successful, or another LDAP error code if it was not. See Section 12.18 for more information about possible errors and how to interpret them.

The `ldap_rename()` and `ldap_rename_s()` functions both support LDAPv3 server controls and client controls.

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