Difference between revisions of "Samba4 Port: hdb & ldb Interfaces"

Revision as of 08:43, 18 September 2009

This page aims to reduce the confusion about four DB libraries:

1. Two hdb libraries in Heimdal;
2. Samba4's hdb_samba4 library (formerly named LDB), and
3. Samba4's ldb library.

These libraries operate as layers:

1. Heimdal's hdb function-pointers wrap hdb_samba4, for Heimdal to retrieve & store entries in the Krb DB.
2. Samba4's hdb_samba4 wraps the most basic store/retrieve part of ldb.
3. Samba4's ldb wraps the underlying database storage

Heimdal's internal hdb handles DB-entries after they're retrieved.

Samba4's hdb_samba4 interface to LDAP

1. These routines make up half of Samba4's kdc-specific code,
2. Almost all of the hdb_samba4_ routines are in source4/kdc/hdb-samba4.c .
3. The exceptionally-placed routine is hdb_samba4_lookup_spn_alias(), in dsdb/samdb .

Heimdal's hdb Interface to Samba4's hdb_samba4

Samba4's file kdc/hdb-samba4.c contains the hdb_samba4_ functions, which only Samba4 uses directly.

In Samba4's heimdal/lib/hdb/hdb.h, Heimdal's HDB structure contains "hdb-" prefixed function-pointers to the hdb_samba4 functions. Only Heimdal uses this function-pointer interface to Samba4's hdb_samba4_ functions:

1. (HDB *)->hdb_dbc = NULL;
2. (HDB *)->hdb_open = hdb_samba4_open;
3. (HDB *)->hdb_close = hdb_samba4_close;
4. (HDB *)->hdb_fetch = hdb_samba4_fetch;
5. (HDB *)->hdb_store = hdb_samba4_store;
6. (HDB *)->hdb_remove = hdb_samba4_remove;
7. (HDB *)->hdb_firstkey = hdb_samba4_firstkey;
8. (HDB *)->hdb_nextkey = hdb_samba4_nextkey;
9. (HDB *)->hdb_lock = hdb_samba4_lock;
10. (HDB *)->hdb_unlock = hdb_samba4_unlock;
11. (HDB *)->hdb_rename = hdb_samba4_rename;
12. (HDB *)->hdb__get = NULL;
13. (HDB *)->hdb__put = NULL;
14. (HDB *)->hdb__del = NULL;
15. (HDB *)->hdb_destroy = hdb_samba4_destroy;
16. (HDB *)->hdb_samba4_check_pkinit_ms_upn_match = hdb_samba4_check_pkinit_ms_upn_match
17. (HDB *)->hdb_samba4_check_constrained_delegation = hdb_samba4_check_constrained_delegation

Samba4's hdb_ library also includes a local function invoked via a function-pointer:

1. hdb_ldb_free_entry in kdc/hdb-samba4.c

This function-pointer gets used by both Heimdal & Samba4.

Heimdal's internal hdb library

This library isn't completely "internal," because four of these routines get used by Samba4, too:

1. initialize_hdb_error_table_r
2. free_hdb_entry
3. hdb_enctype2key
4. hdb_free_entry

Further, the global struct hdb_kt_ops{} gets used only by Samba4.

Two functions here, hdb_lock & hdb_unlock, have the same names as two of the hdb_samba4 function-pointers (see above):

1. (HDB *)->hdb_lock ,
2. (HDB *)->hdb_unlock .

Heimdal uses these two function pointers heavily.

Of these 72 functions:

1. Four get used by Samba4;
2. Seven are used by Heimdal's kdc & tgs code;
3. Seven are used by Heimdal's NDBM & DB code (Heiumdal's alternatives to Samba's ldb);
4. 27 are used only internally, by the hdb library.
5. 39 are unused.

Samba's internal ldb library

These routines are defined & used only in Samba4, and not in Samba4's heimdal snapshot tree. The ldb functions are used by Samba4's hdb_samba4 interface, which Heimdal does use, via the hdb_*** function-pointers.

Key to the columns:

1. *srv : used by rpc_server, smb_server, etc (7 *_server components in all).
2. dsdb : used by dsdb/samdb
3. net  : used by libnet
4. ldb  : used by ldb itself
5. other: used by other components, listed in the function's "other" cell
6. ldb grp: a makeshift subgrouping of ldb, for sorting the functions by type.

The column-headings are clickable.